Abstract
Vaccine hesitancy (VH) is considered a top-10 global health threat. The concept of VH has been described and applied inconsistently. This systematic review aims to clarify VH by analysing how it is operationalized. We searched PubMed, Embase and PsycINFO databases on 14 January 2022. We selected 422 studies containing operationalizations of VH for inclusion. One limitation is that studies of lower quality were not excluded. Our qualitative analysis reveals that VH is conceptualized as involving (1) cognitions or affect, (2) behaviour and (3) decision making. A wide variety of methods have been used to measure VH. Our findings indicate the varied and confusing use of the term VH, leading to an impracticable concept. We propose that VH should be defined as a state of indecisiveness regarding a vaccination decision.
Similar content being viewed by others
Main
In 2019, vaccine hesitancy (VH) was named by the World Health Organization (WHO) as one of the top-10 threats to global health, following a five-fold global increase in measles, a disease that can be prevented by vaccination1,2. The largest increase was reported in the WHO regions covering Europe and the Americas2. The impact of these measles outbreaks is substantial, with rises in morbidity, mortality and costs3,4,5. The increasing incidence of measles and other vaccine-preventable diseases has been attributed to a failure to reach adequate immunization coverage rates2,6. In the European region, VH has been identified as the main barrier to vaccination coverage7,8. This is in contrast to other regions, such as sub-Saharan Africa, where immunization coverage rates are challenged by a combination of barriers, including access and availability9.
In the past decade, VH has become a key topic of research in various fields, following rises in vaccine-preventable diseases, the introduction of new vaccines, the spread of misinformation and lagging vaccination coverage10. Moreover, the COVID-19 pandemic has drawn further attention to the role of VH in limiting the uptake of vaccines and failure to achieve collective immunity11,12,13. This has led to the proliferation of scientific literature on VH in the public health, biomedical and social science research fields10.
In 2012, the WHO established a strategic advisory group of experts (SAGE) working group with the mandate of defining VH and suggesting how to monitor and address it. The working group proposed a broad definition, describing a VH continuum from acceptance to refusal of vaccines or as a delay in acceptance or refusal despite the availability of the vaccines. The working group described VH as “A complex behavioural phenomenon specific to vaccines, context, time, and place and influenced by factors of complacency, convenience, and confidence”14. This broad definition emphasizes variability by describing that VH may vary between types of vaccines and different contexts, may change over time or between different geographical locations and is influenced by various determinants.
The concept of VH has been described and applied in various ways. When definitions are broad and lack clarity, this can lead to the emergence of different concepts with overlapping domains, with various concepts being used interchangeably by some and recognized as distinct entities by others15. Additionally, lack of conceptual clarity can lead to inadequate operationalization and cause confusion among researchers15. This is problematic because when studies use similar terminology with a different meaning, their results are incomparable across subgroups, locations or contexts. A clear conceptualization is needed to develop meaningful measures allowing comparison of results16.
A lack of conceptual clarity is observed in the literature on VH, where VH is variously conceptualized as a psychological state and as different types of vaccination behaviour17,18. In addition, the terms ‘vaccine confidence’, ‘low uptake’ and ‘low intention to vaccinate’ are often equated with VH19,20. Confusion among researchers is then illustrated by inconsistencies in the applied definitions21,22. It has even been argued that VH is a catch-all category, aggregating many different concepts rather than being one measurable construct; and this is impeding progress in the research field23.
A good concept definition consists of characteristics, attributes or features that are unique to that concept and distinguish it from other closely related concepts15. Given the importance of VH for predicting and influencing individual vaccination decisions, it is important to explore the uses of VH and propose an optimal operationalization, distinguishing VH from other closely related concepts. Such clarification could enable a universally adopted definition and aid further research in this area.
The purpose of this systematic review was to provide an overview of how VH is operationalized in the literature in terms of conceptualizations, subpopulations and measurements. Following an assessment of the various conceptualizations, we differentiated the common themes, related concepts, research fields and vaccine types. The scope and structure of this systematic review is visualized in Fig. 1. On the basis of an interpretation of these findings, we suggest a way forward by proposing a renewed definition for VH.
Aiming to give an overview of VH, we recognize three types of operationalizations: conceptualizations (blue), identification of subpopulations (orange) and measurements (green). Conceptualizations of VH are analysed at three levels: (1) common themes, (2) closely related concepts and (3) potential variation in conceptualization between research field and vaccine type. Each type of operationalization and its levels are discussed in separate sections.
Results
Study selection and characteristics
The search strategy yielded 7,427 publications. After screening the titles and abstracts, 919 publications were selected for full-text screening. A total of 420 publications met the inclusion criteria. Seven additional studies were found through citation searching, two of which met the inclusion criteria, adding up to a total of 422 studies. Some studies met the criteria of more than one category, with 36 studies categorized under VH conceptualizations, 63 under VH subpopulations and 373 under VH measurements. The search process is summarized in the PRISMA flow chart (Fig. 2)24. The characteristics of included studies are described in more detail in Supplementary Table 1.
Visualization of the process involving identification of records from databases, screening of records, assessing reports for eligibility, inclusion of eligible studies and exclusion of non-eligible reports with reasons for exclusion. The number of records or reports in each step of the process is shown in brackets.
The included studies cover a wide geographical distribution. The limited majority (54%) originated in high-income countries (HIC), mainly the United States, Canada, Italy, Australia and France. A smaller group (43%) originated in low- and middle-income countries (LMICs), primarily China, India and Turkey. The remaining studies (3%) originated in a combination of HIC and LMICs. The majority (60%) were published in 2021 and 2022.
The included studies approach VH in relation to various vaccine types: 51% pertaining to COVID-19, 29% to childhood, 4% to human papillomavirus, 4% to influenza and 2% to miscellaneous vaccines. Additionally, 11% of the studies concern vaccines in general. Various research fields are represented, including public health (43%), biomedical science (30%), paediatrics (15%) and social sciences (12%). Mixed methods appraisal tool (MMAT) scores were calculated for 88% of the included studies, while the others could not be assessed due to their study types. The majority (68%) scored 3 or higher, indicating that 60% of the quality criteria were met.
Vaccine hesitancy conceptualization
From the 36 studies on VH conceptualization, we extracted and analysed 304 excerpts. Supplementary Table 2 shows the extracted text excerpts for each study. Our thematic analysis revealed that 93 excerpts describe an overall characterization of VH. The majority of these (69%) describe the nature of VH as heterogenous14,21,23,25,26,27,28,29,30,31,32,33,34,35,36,37, complex14,18,20,21,22,23,25,26,29,33,35,38,39,40,41,42,43 or varied, depending on the type of vaccine and the context14,18,20,21,23,27,28,30,33,35,37,38,39,40,41,42,43,44.
VH is conceptualized in 208 excerpts. The thematic analysis revealed three predominant conceptualizations in 165 (79%) excerpts: cognitions or affect, behaviour and decision making. These three conceptualizations overlap in the majority of the studies and excerpts. Illustrative excerpts of each conceptualization are presented in Table 1. The remaining 45 (22%) excerpts represent a fragmented group of conceptualizations, without emerging themes.
Vaccine hesitancy conceptualized as cognitions or affect
From all 36 studies14,17,18,20,21,22,23,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53, 98 excerpts were extracted as conceptualizing VH in terms of cognitions or affect, including questioning, emotions or beliefs regarding vaccination. For this conceptualization, we rank-ordered the most frequently used descriptions of VH, including having or expressing concerns21,25,26,27,29,30,34,35,36,40,42,43,46,51,53, doubts21,28,29,36,43 or questions21,26,47 and being reluctant23,27,29,32,36,38,45,49,53,54 or unsure14,21,27,29,34. Many authors describe VH as pertaining to beliefs34,49, attitudes21,26,37,43,51 or both23,29,30,55. Furthermore, vaccine-hesitant individuals are described as ambivalent to vaccination or perceiving ambiguity in vaccine-related risks21,36,50,53.
Vaccine hesitancy conceptualized as behaviour
From 35 studies14,17,18,20,21,22,23,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52, 94 excerpts were extracted as conceptualizing VH as a behaviour. The majority of the excerpts describe VH in terms of various behaviours14,18,20,21,22,23,25,26,27,29,31,32,34,35,37,38,39,40,41,44,45,51, as illustrated by the following example: “VH refers to a ‘delay’ in acceptance or ‘refusal’ of vaccines”14. Other excerpts describe VH as a range or continuum between the extreme ends of accepting all vaccines and refusing all vaccines21,22,27,28,29,30,31,33,36,38,43. In a minority of the excerpts, VH is described as a specific type of vaccination behaviour, including vaccinating as recommended (despite reluctance, concerns or feeling unsure)26,46,47,49, refusing vaccines28 or delaying vaccines and choosing an alternative schedule50. Some studies explicitly state that VH should not be described as a vaccination behaviour17,18,36,40. Within articles, there were inconsistencies in the behavioural descriptions of VH18,22,26,27,28,29,31,38,41.
Vaccine hesitancy conceptualized as decision making
From 19 studies18,21,23,26,27,30,31,32,36,37,38,40,42,44,45,50,52,53, 30 excerpts were extracted as conceptualizing VH in terms of vaccine decision-making. Some authors adopt the term VH when describing individuals who are undecided, indecisive or under consideration, and not yet having made a final vaccine decision21,23,26,31,32,45,50. Vaccine-hesitant individuals are described as being in various states of indecision23,31,32,37 or as seeking more information to make ‘the right decision’ about vaccination21,53. Moreover, some authors describe VH as an approach to38 or a transient stage in the process of vaccine decision-making itself21,23,37.
Vaccine hesitancy and related concepts
VH is often described in relation to other concepts. We extracted 142 excerpts from 31 studies describing closely related concepts14,18,20,21,22,23,25,26,27,29,30,32,33,34,35,36,38,39,40,41,42,43,44,45,46,47,48,50,51,52,53. The three most common concepts are confidence or trust, complacency and convenience. Together, these are referred to as ‘the 3 Cs’14 and described in 69 of 142 (49%) excerpts. Most often, the 3 Cs are described as having a causal relationship with VH and as representing determinants14,18,20,29,33,35,38,41,48,56.
From 25 studies, 46 excerpts were extracted as describing confidence14,18,20,21,22,23,25,26,27,29,30,33,34,35,36,38,39,41,42,43,44,46,47,48,52. ‘Confidence’ is defined as the trust that people have in the immunizations, the healthcare system itself, and the process leading to decisions on licensing or recommended schedules14,27,35. Few studies describe the (lack of) trust or confidence as a component of VH23,34,52.
From 22 studies14,18,20,21,22,23,25,26,29,30,33,35,38,39,40,41,43,44,47,48,50,52, 41 excerpts were extracted on the theme of complacency. ‘Complacency’ is the individual evaluation of the risks and benefits of vaccines and of the need to vaccinate14,18,20,35. The concept of complacency in relation to VH is described as the tendency to perceive the risks of vaccination as unknown or disproportionally high and the risks of the vaccine-preventable disease as low44,50. Vaccine-hesitant individuals are more committed to assessing vaccine risks and seeking ways to minimize them23,40,47,50.
From 15 studies14,18,20,21,22,25,29,33,35,38,39,41,42,43,48, 27 excerpts were extracted as describing the theme of convenience. ‘Convenience’ concerns not only physical availability and geographical accessibility of vaccines, but also the user-friendliness of and ability to understand immunization services14,18,35,42. In our analysis, we found that many authors refer to convenience by describing VH as the delaying or refusal of vaccines ‘despite availability’14,18,21,22,23,25,26,29,33,35,38,39,41. This description acknowledges that availability of vaccines is related to vaccine uptake, while VH itself is not influenced by availability issues. However, one study adopts inconvenience and difficulty to access vaccines as dimensions of VH42.
Variations between research fields and vaccine types
We identified the respective research field and vaccine type of each study in the qualitative analysis to explore related differences in descriptions of VH. We identified 19 public health studies18,21,23,25,26,27,28,29,32,33,36,37,38,41,45,47,50,51,53, 6 paediatric studies14,31,34,35,39,48, 8 social science studies17,20,22,42,44,46,49,52 and 3 biomedical studies30,40,43. The primary difference observed was that conceptualizations of VH in terms of decision making emerged predominantly in the public health18,21,23,32,38,50,54 and social science fields42,44,52. In studies conceptualizing VH in terms of cognitions or affect, the terms ‘beliefs’ and ‘concerns’ were used in all research fields, while ‘reluctance’, ‘doubts’ and ‘questions’ were used almost exclusively in the public health field. The conceptualization of VH as a behaviour occurred in all research fields.
VH was discussed in relation to vaccination in general14,17,18,22,23,27,28,29,32,33,35,36,38,41,42,43,46,48,49 or specifically with regard to childhood vaccines21,25,26,30,31,34,37,39,40,47,50,51,53, in 19 and 13 of the studies, respectively. The remaining 4 studies discussed VH in relation to COVID-1944,45,52 and influenza20. Our analysis compared the studies on general vaccination and childhood vaccines but found no major differences in their respective conceptualizations.
Vaccine hesitancy subpopulations
Of the 422 included studies, 63 identified various VH subpopulations. We extracted text excerpts describing the classifications of these subpopulations and the authors’ rationales for the distinctions. The analysis identified themes aligned with the three VH conceptualization categories. Fourteen studies grouped VH subpopulations on the basis of criteria from the conceptualization as cognitions or affect21,23,57,58,59,60,61,62,63,64,65,66,67,68 and 3 studies grouped VH on the basis of the conceptualization of decision making69,70,71. VH subpopulations grouped solely on the basis of criteria from the behaviour conceptualization were not found. However, 19 studies grouped hesitant individuals on the basis of criteria from the conceptualizations of both cognitions or affect, and behaviour26,47,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88. The remaining 27 studies did not identify subpopulations in terms of the three conceptualizations. Twelve studies identified subpopulations on the basis of degree of VH51,89,90,91,92,93,94,95,96,97,98,99. Although degree of VH does not directly contribute to understanding of the VH concept, the instruments used to quantify it and determine cut-off values for the subpopulations contain valuable information about the operationalizations. These instruments are discussed in the following section. In addition, a group of 10 studies distinguished a VH subpopulation by asking about willingness to be vaccinated but used different criteria to do so100,101,102,103,104,105,106,107,108,109. This method was mainly found in studies on COVID-19 vaccination, published in 2021. This demonstrates the emergence of a conceptual VH category that was not identified from the conceptual studies. The final 5 studies grouped subpopulations according to miscellaneous criteria45,49,110,111,112. An overview is provided Supplementary Table 3.
Measurements of vaccine hesitancy
Of the 422 studies included, 373 report a measurement of VH in individuals. An overview is provided in Supplementary Table 4, grouping the studies according to the instruments used. The most common, albeit highly heterogenous, method used in 210 (56%) studies is a brief VH assessment comprising 1–3 questions64,65,66,68,71,74,75,84,85,88,90,96,97,98,100,102,103,105,106,107,108,109,111,113,114,115,116,117,118,119,120,121,122,123,124,125,126,127,128,129,130,131,132,133,134,135,136,137,138,139,140,141,142,143,144,145,146,147,148,149,150,151,152,153,154,155,156,157,158,159,160,161,162,163,164,165,166,167,168,169,170,171,172,173,174,175,176,177,178,179,180,181,182,183,184,185,186,187,188,189,190,191,192,193,194,195,196,197,198,199,200,201,202,203,204,205,206,207,208,209,210,211,212,213,214,215,216,217,218,219,220,221,222,223,224,225,226,227,228,229,230,231,232,233,234,235,236,237,238,239,240,241,242,243,244,245,246,247,248,249,250,251,252,253,254,255,256,257,258,259,260,261,262,263,264,265,266,267,268,269,270,271,272,273,274,275,276,277,278,279,280,281,282,283,284,285,286,287,288,289,290,291,292,293,294,295,296,297,298. The questions, as well as the criteria or cut-off points used to define hesitancy, vary widely between the studies. The majority of questions used in this method cover operationalizations of VH that did not emerge from our conceptual analysis, including intention and willingness. A group of 124 studies assess VH by asking about vaccination intention. For example, one measurement asks “What would you do if a COVID-19 vaccine were available?”. Respondents answering either “I would eventually get a vaccine, but wait a while first”, “I would not get a vaccine” or “I’m not sure” are all classified as hesitant169. A group of 35 studies assess VH by asking about willingness, exemplified by the question: “Are you willing to receive the COVID-19 vaccination?”. Respondents answering “yes, but I choose to delay timing of injection” are considered hesitant100. Furthermore, 23 studies assess VH by an explicit verbatim assessment of experienced hesitancy levels. This is exemplified by the question: “Overall, how hesitant about childhood vaccines would you consider yourself to be?”. Respondents answering “not too hesitant”, “not sure”, “somewhat hesitant” or “very hesitant” are considered hesitant136. Finally, a minority of 14 studies assess VH with questions covering conceptualizations that did emerge from our conceptual analysis; for example, by asking about previous vaccination behaviour: “Have you ever hesitated, delayed, or refused getting a vaccination for your child or yourself due to reasons other than allergies and sickness?”. Respondents answering “yes” to this question are considered hesitant122. The remaining 14 studies use miscellaneous questions to assess VH. Notably, the intention and willingness measures to assess VH are found mainly in studies published in 2021 on COVID-19 vaccination, while the other methods have been used throughout the covered period and in the context of different vaccines.
The second most common method, applied by 132 (35%) studies, is the use of a validated instrument. The most common instrument, used in 70 studies, is the parent attitudes about childhood vaccines (PACV) survey, introduced by Opel et al.34. The PACV consists of 15 questions about immunization behaviour, beliefs about vaccine safety and efficacy, attitudes toward vaccine mandates and exemptions, and trust299, thereby operationalizing VH as both cognitions or affect, and behaviour. Trust (or confidence) is also included in this instrument. In our conceptual analysis, confidence emerged as a distinct concept, albeit closely related to VH. Clear cut-off points for hesitancy were formulated and applied in the vast majority of the studies using this instrument (shown in Supplementary Table 4). The PACV is variously used in its original form34,91,299,300,301,302,303,304,305,306,307,308,309,310,311,312,313,314,315,316,317,318,319,320,321,322,323,324,325,326,327,328,329,330,331,332,333,334,335,336,337,338, or in adapted339,340,341,342,343,344,345,346,347,348,349,350,351,352,353,354,355 or shorter versions51,62,89,93,95,356,357,358,359,360,361.
Other studies use a variety of validated and broadly used instruments. The SAGE instrument is applied in 13 of the studies41,362,363,364,365,366,367,368,369,370,371,372,373, with questions reflecting the different conceptualizations (cognitions or affect, behaviour and decision making) and related concepts including convenience, complacency and confidence41. The vaccine hesitancy scale (VHS), used in 39 studies83,99,374,375,376,377,378,379,380,381,382,383,384,385,386,387,388,389,390,391,392,393,394,395,396,397,398,399,400,401,402,403,404,405,406,407,408,409,410, was derived from a subscale of the SAGE instrument, narrowed to conceptualize VH as cognitions or affect and include the related concept of confidence69. The studies using the SAGE instrument and VHS use varying outcomes or cut-off values (or no outcomes or cut-off values at all) to define hesitancy (shown in Supplementary Table 4). The Oxford COVID-19 vaccine hesitancy scale was recently designed exclusively for the assessment of VH for COVID-19 vaccination and subsequently applied in 5 studies44,411,412,413,414. Other instruments described in the context of VH but intended to assess other concepts include the 5C scale22 of psychological antecedents of vaccine behaviour, the vaccine acceptance scale (which covers the domains cognitions and affects, confidence and legitimacy of government vaccine mandates46) and the multidimensional vaccine hesitancy scale covering perceptions regarding vaccines in general42. Instruments assessing confidence have also been applied to assess hesitancy415.
The remaining 31 (8%) studies use a variety of unique, self-developed methods to measure hesitancy. These are classified as ‘miscellaneous’25,50,52,69,73,92,94,416,417,418,419,420,421,422,423,424,425,426,427,428,429,430,431,432,433,434,435,436,437,438,439. Examples include measurement of VH based on vaccination rates from medical records418 and statistical procedures used to group participants according to their patterned responses to a questionnaire92,439.
Discussion
Our systematic review reveals that VH is conceptualized in the literature as involving cognitions or affect, behaviour and decision making, representing three distinct but interacting entities. Closely related concepts include confidence or trust, perceptions of the need to vaccinate and of risk (complacency), and convenience. VH subpopulations are grouped according to a variety of criteria, with the majority originating in the three identified conceptualizations. Studies measuring VH have used a wide variety of instruments. The most commonly applied instruments include a brief assessment comprising 1–3 variable questions and the PACV for childhood vaccines. The instruments operationalize hesitancy using one or more of the three identified conceptualizations, but also introduce novel conceptualizations including intention and willingness. When synergizing the findings on different VH operationalizations, we found psychological and behavioural operationalizations, with the psychological operationalizations being cognitions or affect, and decision making.
Our findings illustrate the challenge of operationalizing VH, with studies adopting different conceptualizations, subpopulations and measurements. Dubé et al. acknowledged this challenge of operationalizing the VH concept due to its heterogeneity and the diversity in attitudes and behaviours29. Furthermore, our findings align with a recent study demonstrating the many interpretations of VH used across Europe440. These inconsistencies in terminology are even evidenced in the Merriam-Webster dictionary, where ‘hesitancy’ is defined as a quality or state of being that involves indecision or reluctance441, aligning with VH conceptualized as decision making and cognitions or affect, while ‘vaccine hesitancy’ is defined as the reluctance or refusal to vaccinate442, thereby also including a conceptualization of behaviour.
In the introduction, we describe interchangeable use of various terms with VH19,20. In our review, we also found numerous examples, including ‘confidence’443, ‘low intention’444 and ‘unwillingness’270. We identify these concepts as related but not synonymous to VH. For instance, some authors note that confidence or trust are used interchangeably in relation to VH19,22, suggesting equivalent meanings. Others describe an inverse relationship, meaning that lower levels of confidence are associated with higher levels of VH19,33,54,56,445. In line with this, VH is described as originating from a lack of confidence446 and as a possible indicator of declining confidence56.
Additionally, in our analysis of subgroups and measurements, we found that VH is frequently operationalized in terms of willingness and intention, which we did not find in our conceptual analysis of VH. Willingness and intention to vaccinate, similar to the ‘vaccine confidence’ concept, are inversely related concepts that are unequivocally linked to VH but are and should not be treated as synonymous. Using these terms interchangeably is not only inappropriate but also contributes to confusion and unclarity of the VH concept. This clarity is needed because unclear concepts give rise to differences in our understanding of its determinants, correlates and consequences, hindering efforts to study and address VH15,23,440. Furthermore, at an operational level, there may be a mismatch between a concept and its measures15. This is demonstrated in our review by the highly variable methods we found to measure VH, leading to incomparable results. Particularly during 2021, there has been a plethora of studies reporting VH measurements that, due to divergent definitions and methods, have been of questionable value. As a way forward, we base our reasoning for a renewed definition of VH on the three main identified conceptual categories—behaviour, cognitions or affect, and decision making—as these have proven most promising by their repeated representation in conceptual, subgroup and measurement studies
We argue that conceptualizing VH as vaccination behaviour is untenable, as mere behaviour is insufficiently discriminating between hesitant and non-hesitant individuals. For instance, people may accept vaccines with or without hesitation or reject vaccines with or without hesitation. As concepts are ideally defined by a unique set of features that distinguishes them from other closely related concepts15, vaccination behaviour alone is not sufficient to define VH. Furthermore, vaccination behaviour is generally used as the indicator of (non-)acceptance of vaccination. Thus, to use this also to define another concept would create confusion. Authors have commented on the blurred distinction between VH and refusal of vaccines25,39 and criticized behavioural operationalization for its failure to capture VH17,18,23,25,40. Although we agree that certain types of vaccination behaviour may be manifestations of VH, we argue that including behaviour in the definition and operationalization of VH is neither necessary nor sufficient.
Our analysis shows that VH is furthermore defined by two closely linked conceptualizations that we identify as psychological—cognitions or affect, and decision making. Larson et al. exemplify this stance, arguing that VH is by nature a state of indecision and reluctance32. We propose to reject types of vaccination behaviour as a viable conceptualization of VH; this logically results in the proposition that VH should be considered a psychological construct. This is in line with authors who have argued that VH is a psychological state rather than a behaviour18,22,26,32,40, inspiring our current investigation of what exactly this vaccine-hesitant state entails. In the conceptualization cognitions or affect, VH is mainly described as ‘doubts’, ‘concerns’ and ‘reluctance’ regarding vaccination. Following our analysis, we interpreted these descriptions as different ways of how VH may be affected, experienced or expressed at an individual level, representing a layer surrounding the central element of VH. We therefore interpret cognitions and affect to go hand-in-hand, but not to be at the core of hesitancy. Moreover, we conclude that cognitions or affect are insufficiently distinctive to define VH.
This interpretation does not mean that the identified cognitions or affect are irrelevant to VH. On the contrary, they may prove crucial in shaping VH. However, to arrive at a clear definition of VH, cognitions and affects should be treated as clearly defined entities as well. Only by unravelling and distinguishing them can the exact nature of their relationship with VH be clarified in further research.
In the conceptualization decision making, VH was described as being ‘undecided’, ‘indecisive’, ‘in consideration’ or ‘not yet making a vaccine decision’. All these descriptions include an element of indecision, and this provides a unique and distinctive feature for VH. Additionally, we found that this conceptualization is predominantly discussed in studies in the public health field. This is rather logical, as one would expect this field of research to take a more pragmatic approach, examining the presence of VH at a stage where people have been offered a vaccine or to anticipate public sentiments around willingness to accept a vaccine when it is offered. This probably triggers a decision-making process where VH can emerge and manifest. On the basis of these findings, we argue that VH is a psychological state of being undecided, indecisive or not yet making a decision regarding vaccination.
The study selection was conducted independently by different members of our research team. However, one possible limitation is that we did not attempt to exclude studies of lower quality, as we wanted to maintain a robust selection of studies to enable a broad overview of the relevant literature. Our MMAT assessment, however, indicates that the majority of the studies are of medium quality. A second limitation is that a considerable number of the included conceptual studies (17 of the 36)14,18,20,21,22,23,25,26,29,35,38,39,40,41,42,43,44 quoted the VH definition introduced by the SAGE working group, which may have led to an amplification of the SAGE definition. This may indicate that this definition is well recognized, but potentially overshadows less recognized conceptual definitions of VH. We chose to include all quoted definitions and found that many studies used more than one. We did not look further into conflicting definitions within the articles, but doing so could yield interesting insights.
In conclusion, we propose a definition of VH as a psychological state of indecisiveness that people may experience when making a decision regarding vaccination. We acknowledge that experiencing concerns, doubts or reluctance regarding vaccination may play a vital role in shaping VH. However, we argue that these factors have the highest potential to advance scientific knowledge when treated as relevant constructs integral to shaping VH, rather than treating them as synonymous to VH. Operationalizing VH by measuring or distinguishing subpopulations should ideally be directed at this state of indecision. To avoid confusion, it is important to separate VH from vaccination behaviour, which is already a well-defined concept. This proposal of a renewed definition of a concept that has been used for a decade could be perceived as ‘putting old wine in new bottles’. However, we feel that due to the large amount of highly varied literature, and given the importance of VH research in predicting, explaining and influencing immunization behaviour, it is necessary to take a snapshot of the status quo. The conclusion of this review is that VH is, for now, an impracticable concept, due to the confusing use of multiple, varied operationalizations. To aid further research, the VH concept must be clearly conceptualized and adapted from its broad and inclusive form to a pragmatic and refined alternative. Working on such an alternative, the field should first reach consensus on the definition and then measure VH accordingly. This approach allows for a much-needed comparison between studies to improve our understanding of VH determinants, correlates and consequences on an individual and societal level. Our way forward is to simplify and clarify the operationalization of VH by returning to its root core of indecisiveness.
Methods
This systematic review was registered on 11 November 2020 in the PROSPERO database (CRD42020211046). The record and study protocol are available at https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=211046.
Search
Relevant publications were searched using the PubMed, Embase and PsycINFO databases to ensure coverage of all relevant research areas in the medical, public health and social science fields. The CINAHL database was also considered, but a pilot search revealed that its unique contributions were limited.
An experienced research librarian used the following keywords to develop a search strategy (Supplementary Methods): ‘vaccination’, ‘immunization’, ‘vaccination refusal’, ‘vaccination avoidance’, ‘vaccination hesitation’, ‘vaccine hesitancy’, ‘vaccine uptake’, ‘vaccination behaviour’, ‘vaccination attitude’, ‘vaccine confidence’, ‘vaccine acceptance’ and ‘vaccine barriers’. The limitations included a publication date of between 2010 and the date of the search (14 January 2022). Conference abstracts were excluded from the search of the Embase database.
Eligibility criteria
The included studies were all published in peer-reviewed journals and written in English. All study types were eligible, except editorials and commentaries, as we sought to include original studies. Studies on animal vaccines were excluded.
The purpose of this review was to clarify the VH concept by analysing how it is operationalized. We recognized operationalizations at two main levels: conceptual and empirical. This resulted in three main groups: (1) studies describing or defining the VH concept and studies applying the concept by (2) identifying VH subpopulations and (3) measuring VH in individuals. This approach allowed comparison between conceptual and empirical operationalizations of VH.
Study selection
In the first selection round, two members of the research team used RAYYAN software to independently assess the titles and abstracts. Studies were selected when the title or abstract contained the term ‘vaccine hesitancy’. Studies were also selected if the title or abstract indicated that the full text contained further information on VH conceptualization, subpopulations or measurements. Papers without an abstract were selected for full-text screening. After double-screening, the results were de-blinded to allow the researchers to discuss their conflicting judgements until consensus was reached.
In the second selection round, the full texts were screened. The first 30% of studies were double-screened to establish a uniform method. Studies were screened on whether they met the criteria for one or more of the three categories (conceptualization, subpopulations and measurements). The category of ‘conceptualization’ included studies that describe, discuss or explore the VH concept or propose a novel VH measurement instrument. Studies falling into only the second category (subpopulations) were excluded if they merely distinguished between hesitant and non-hesitant groups, since a dichotomous grouping does not contribute to understanding of VH. The references from the included full-text articles were screened to find additional studies matching the selection criteria.
We deviated posthoc from our preregistered study protocol by adjusting the study selection criteria as follows. Initially, we also included studies containing the term ‘vaccine confidence’ (that is, with no mention or operationalization of vaccine hesitancy) as indicated in our study protocol. During the process, we realized that this deviated from our primary aim to clarify the VH concept by differentiating its related concepts. Therefore, we adapted the protocol and excluded 16 studies that were exclusively on vaccine confidence from our analysis
Data collection
The study characteristics were extracted from each of the full-text articles. Data were extracted by one researcher and verified by a second member of the research team. The variables included the first author, year of publication, research field of the first author, type of study, type of participants, number of participants, type of vaccination and country in which the study was conducted (with corresponding economic status)447. For the studies that do not include data collection, the country of origin was determined using the affiliation of the first author.
From the studies on VH conceptualization, text excerpts that define or describe VH or describe the relationship of VH to other concepts were extracted. These excerpts were further analysed in the qualitative analysis. From studies that describe different VH subpopulations, information about the categorization of these various subgroups was extracted, including the rationale for the distinguished subpopulations. From studies that describe VH measurements, the instrument(s) and criteria used to define VH were extracted.
Synthesis of results
The text excerpts extracted from the studies conceptualizing VH were thematically coded using ATLAS.ti software. Three research team members developed a coding book of themes and subthemes after independent coding of 30% of the studies. Thereafter, one researcher continued the coding process for the remaining studies. Any emerging new codes were discussed with the other research team members. The results were analysed qualitatively, and the predominant themes were identified by the three team members. When possible, results were grouped by research field and vaccine type to allow for comparison.
The data extracted from the studies describing VH subpopulations were summarized in a table and grouped according to the common themes identified. The data extracted from the studies describing a VH measurement were summarized in a table and grouped according to the instrument or method used. Where multiple measurement instruments are used in one study, the tool used to determine hesitancy was selected as the main instrument.
Quality assessment
The quality of each study was assessed using the MMAT448. This tool contains appraisal guidelines for different study types, covering the majority of the included studies. An overall score was calculated (1–5) on the basis of additional communication about the MMAT 2018 version, with higher scores indicating higher quality levels449. The first 20% of studies were assessed independently by two members of the research team to ensure consistency. Thereafter, one member of the research team continued the assessment.
Reporting summary
Further information on research design is available in the Nature Research Reporting Summary linked to this article.
Data availability
All data generated or analysed during this study are included in this article and its Supplementary Information. This systematic review is registered in PROSPERO (CRD42020211046).
References
Ten Threats to Global Health in 2019 (WHO, 2019); https://www.who.int/news-room/spotlight/ten-threats-to-global-health-in-2019
Patel, M. K. et al. Progress toward regional measles elimination - worldwide, 2000–2019. MMWR Morb. Mortal. Wkly Rep. 69, 1700–1705 (2020).
Suijkerbuijk, A. W. et al. Economic costs of measles outbreak in the Netherlands, 2013–2014. Emerg. Infect. Dis. 21, 2067–2069 (2015).
Ghebrehewet, S. et al. The economic cost of measles: healthcare, public health and societal costs of the 2012–13 outbreak in Merseyside, UK. Vaccine 34, 1823–1831 (2016).
Chovatiya, R. & Silverberg, J. I. Inpatient morbidity and mortality of measles in the United States. PLoS ONE 15, e0231329 (2020).
Feemster, K. A. & Szipszky, C. Resurgence of measles in the United States: how did we get here? Curr. Opin. Pediatr. 32, 139–144 (2020).
Rechel, B., Richardson, E. & McKee, M. The Organization and Delivery of Vaccination Services in the European Union (The European Observatory on Health Systems and Policies, 2018). https://www.euro.who.int/__data/assets/pdf_file/0008/386684/vaccination-report-eng.pdf
Wilder-Smith, A. B. & Qureshi, K. Resurgence of measles in Europe: a systematic review on parental attitudes and beliefs of measles vaccine. J. Epidemiol. Glob. Health 10, 46–58 (2020).
Bangura, J. B., Xiao, S., Qiu, D., Ouyang, F. & Chen, L. Barriers to childhood immunization in sub-Saharan Africa: a systematic review. BMC Public Health 20, 1108 (2020).
Sweileh, W. M. Bibliometric analysis of global scientific literature on vaccine hesitancy in peer-reviewed journals (1990–2019). BMC Public Health 20, 1252 (2020).
Frederiksen, L. S. F., Zhang, Y., Foged, C. & Thakur, A. The long road toward COVID-19 herd immunity: vaccine platform technologies and mass immunization strategies. Front. Immunol. 11, 1817 (2020).
Randolph, H. E. & Barreiro, L. B. Herd immunity: understanding COVID-19. Immunity 52, 737–741 (2020).
Dror, A. A. et al. Vaccine hesitancy: the next challenge in the fight against COVID-19. Eur. J. Epidemiol. 35, 775–779 (2020).
MacDonald, N. E. Vaccine hesitancy: definition, scope and determinants. Vaccine 33, 4161–4164 (2015).
Podsakoff, P. M., MacKenzie, S. B. & Podsakoff, N. P. Recommendations for creating better concept definitions in the organizational, behavioral, and social sciences. Organ. Res. Methods 19, 159–203 (2016).
Shapiro, G. K. et al. A critical review of measures of childhood vaccine confidence. Curr. Opin. Immunol. 71, 34–45 (2021).
Brewer, N. T., Chapman, G. B., Rothman, A. J., Leask, J. & Kempe, A. Increasing vaccination: putting psychological science into action. Psychol. Sci. Public Interest 18, 149–207 (2017).
Bedford, H. et al. Vaccine hesitancy, refusal and access barriers: the need for clarity in terminology. Vaccine 36, 6556–6558 (2018).
Orenstein, W. et al. Assessing the state of vaccine confidence in the United States: recommendations from the national vaccine advisory committee. Public Health Rep. 130, 573–595 (2015).
Schmid, P., Rauber, D., Betsch, C., Lidolt, G. & Denker, M. L. Barriers of influenza vaccination intention and behavior - a systematic review of influenza vaccine hesitancy, 2005–2016. PLoS ONE 12, e0170550 (2017).
Dubé, E. et al. “Nature does things well, why should we interfere?”: vaccine hesitancy among mothers. Qual. Health Res. 26, 411–425 (2016).
Betsch, C. et al. Beyond confidence: development of a measure assessing the 5C psychological antecedents of vaccination. PLoS ONE 13, e0208601 (2018).
Peretti-Watel, P., Larson, H. J., Ward, J. K., Schulz, W. S. & Verger, P. Vaccine hesitancy: clarifying a theoretical framework for an ambiguous notion. PLoS Curr. https://doi.org/10.1371/currents.outbreaks.6844c80ff9f5b273f34c91f71b7fc289 (2015).
Page, M. J. et al. The PRISMA 2020 statement: an updated guideline for reporting systematic reviews. Brit. Med. J. 372, n71 (2021).
Bertoncello, C. et al. Socioeconomic determinants in vaccine hesitancy and vaccine refusal in Italy. Vaccines 8, 276 (2020).
Deml, M. J. et al. ‘Problem patients and physicians’ failures’: what it means for doctors to counsel vaccine hesitant patients in Switzerland. Soc. Sci. Med. 255, 112946 (2020).
Dubé, E. et al. Vaccine hesitancy: an overview. Hum. Vaccin. Immunother. 9, 1763–1773 (2013).
Dubé, E., Gagnon, D., Nickels, E., Jeram, S. & Schuster, M. Mapping vaccine hesitancy–country-specific characteristics of a global phenomenon. Vaccine 32, 6649–6654 (2014).
Dubé, E. et al. Understanding vaccine hesitancy in Canada: results of a consultation study by the Canadian Immunization Research Network. PLoS ONE 11, e0156118 (2016).
Gowda, C. & Dempsey, A. F. The rise (and fall?) of parental vaccine hesitancy. Hum. Vaccin. Immunother. 9, 1755–1762 (2013).
Kestenbaum, L. A. & Feemster, K. A. Identifying and addressing vaccine hesitancy. Pediatr. Ann. 44, e71–e75 (2015).
Larson, H. J. Negotiating vaccine acceptance in an era of reluctance. Hum. Vaccin. Immunother. 9, 1779–1781 (2013).
Oduwole, E. O., Pienaar, E. D., Mahomed, H. & Wiysonge, C. S. Current tools available for investigating vaccine hesitancy: a scoping review protocol. BMJ Open 9, e033245 (2019).
Opel, D. J. et al. Development of a survey to identify vaccine-hesitant parents: the parent attitudes about childhood vaccines survey. Hum. Vaccin. 7, 419–425 (2011).
Smith, M. J. Promoting vaccine confidence. Infect. Dis. Clin. North Am. 29, 759–769 (2015).
Dubé, È., Ward, J. K., Verger, P. & MacDonald, N. E. Vaccine hesitancy, acceptance, and anti-vaccination: trends and future prospects for public health. Annu Rev. Public Health 42, 175–191 (2021).
Popper-Giveon, A. & Keshet, Y. Non-Vaccination Stage Model (NVST): the decision-making process among Israeli ultra-orthodox Jewish parents. Health https://doi.org/10.1177/1363459320988884 (2021).
Kumar, D., Chandra, R., Mathur, M., Samdariya, S. & Kapoor, N. Vaccine hesitancy: understanding better to address better. Isr. J. Health Policy Res. 5, 2 (2016).
McIntosh, E. D., Janda, J., Ehrich, J. H., Pettoello-Mantovani, M. & Somekh, E. Vaccine hesitancy and refusal. J. Pediatr. 175, 248–249.e1 (2016).
Díaz Crescitelli, M. E. et al. A meta-synthesis study of the key elements involved in childhood vaccine hesitancy. Public Health 180, 38–45 (2020).
Larson, H. J. et al. Measuring vaccine hesitancy: the development of a survey tool. Vaccine 33, 4165–4175 (2015).
Howard, M. C. A more comprehensive measure of vaccine hesitancy: creation of the Multidimensional Vaccine Hesitancy Scale (MVHS). J. Health Psychol. https://doi.org/10.1177/13591053211042062 (2021).
Turner, P. J., Larson, H., Dubé, È. & Fisher, A. Vaccine hesitancy: drivers and how the allergy community can help. J. Allergy Clin. Immunol. Pract. 9, 3568–3574 (2021).
Freeman, D. et al. COVID-19 vaccine hesitancy in the UK: the Oxford coronavirus explanations, attitudes, and narratives survey (Oceans) II. Psychol. Med. https://doi.org/10.1017/s0033291720005188 (2020).
Su, Z. et al. A race for a better understanding of COVID-19 vaccine non-adopters. Brain Behav. Immun. Health 9, 100159 (2020).
Sarathchandra, D., Navin, M. C., Largent, M. A. & McCright, A. M. A survey instrument for measuring vaccine acceptance. Prev. Med. 109, 1–7 (2018).
Leask, J. et al. Communicating with parents about vaccination: a framework for health professionals. BMC Pediatr. 12, 154 (2012).
Jankovic, S. Childhood vaccination in the twenty-first century: parental concerns and challenges for physicians. Arh. Farm. 69, 452–468 (2019).
Hagood, E. A. & Mintzer Herlihy, S. Addressing heterogeneous parental concerns about vaccination with a multiple-source model: a parent and educator perspective. Hum. Vaccin. Immunother. 9, 1790–1794 (2013).
Blaisdell, L. L., Gutheil, C., Hootsmans, N. A. & Han, P. K. Unknown risks: parental hesitation about vaccination. Med. Decis. Mak. 36, 479–489 (2016).
Amin, A. B. et al. Association of moral values with vaccine hesitancy. Nat. Hum. Behav. 1, 873–880 (2017).
Kotta, I., Kalcza-Janosi, K., Szabo, K. & Marschalko, E. E. Development and validation of the multidimensional COVID-19 vaccine hesitancy scale. Hum. Vaccin. Immunother. 18, 1–10 (2021).
Sjögren, E., Ask, L. S., Örtqvist, Å. & Asp, M. Parental conceptions of the rotavirus vaccine during implementation in Stockholm: a phenomenographic study. J. Child Health Care 21, 476–487 (2017).
Frew, P. M. et al. Development of a US trust measure to assess and monitor parental confidence in the vaccine system. Vaccine 37, 325–332 (2019).
Smith, J. C., Appleton, M. & MacDonald, N. E. Building confidence in vaccines. Adv. Exp. Med. Biol. 764, 81–98 (2013).
Larson, H. J., Schulz, W. S., Tucker, J. D. & Smith, D. M. Measuring vaccine confidence: introducing a global vaccine confidence index. PLoS Curr. https://doi.org/10.1371/currents.outbreaks.ce0f6177bc97332602a8e3fe7d7f7cc4 (2015).
Ramanadhan, S., Galarce, E., Xuan, Z., Alexander-Molloy, J. & Viswanath, K. Addressing the vaccine hesitancy continuum: an audience segmentation analysis of american adults who did not receive the 2009 H1N1 vaccine. Vaccines 3, 556–578 (2015).
Rossen, I., Hurlstone, M. J., Dunlop, P. D. & Lawrence, C. Accepters, fence sitters, or rejecters: moral profiles of vaccination attitudes. Soc. Sci. Med. 224, 23–27 (2019).
Rozbroj, T., Lyons, A. & Lucke, J. Vaccine-hesitant and vaccine-refusing parents’ reflections on the way parenthood changed their attitudes to vaccination. J. Community Health 45, 63–72 (2020).
Schwartz, J. L. & Caplan, A. L. Vaccination refusal: ethics, individual rights, and the common good. Prim. Care 38, 717–728 (2011).
Shay, L. A. et al. Parent-provider communication of HPV vaccine hesitancy. Pediatrics 141, e20172312 (2018).
Oladejo, O. et al. Comparative analysis of the Parent Attitudes about Childhood Vaccines (PACV) short scale and the five categories of vaccine acceptance identified by Gust et al. Vaccine 34, 4964–4968 (2016).
Bouchez, M. et al. Physicians’ decision processes about the HPV vaccine: a qualitative study. Vaccine 39, 521–528 (2021).
Elwy, A. R. et al. Vaccine hesitancy as an opportunity for engagement: a rapid qualitative study of patients and employees in the U.S. Veterans Affairs healthcare system. Vaccine 9, 100116 (2021).
Paris, C. et al. COVID-19 vaccine hesitancy among healthcare workers. Infect. Dis. Now 51, 484–487 (2021).
Tram, K. H. et al. Deliberation, dissent, and distrust: understanding distinct drivers of COVID-19 vaccine hesitancy in the United States. Clin. Infect. Dis. https://doi.org/10.1093/cid/ciab633 (2021).
Vulpe, S. N. & Rughiniş, C. Social amplification of risk and “probable vaccine damage”: a typology of vaccination beliefs in 28 European countries. Vaccine 39, 1508–1515 (2021).
Wang, M. W. et al. COVID-19 vaccination acceptance among healthcare workers and non-healthcare workers in china: a survey. Front. Public Health 9, 709056 (2021).
Shapiro, G. K. et al. Using an integrated conceptual framework to investigate parents’ HPV vaccine decision for their daughters and sons. Prev. Med. 116, 203–210 (2018).
Tatar, O., Shapiro, G. K., Perez, S., Wade, K. & Rosberger, Z. Using the precaution adoption process model to clarify human papillomavirus vaccine hesitancy in Canadian parents of girls and parents of boys. Hum. Vaccin. Immunother. 15, 1803–1814 (2019).
Dubov, A. et al. Predictors of COVID-19 vaccine acceptance and hesitancy among healthcare workers in Southern California: not just “anti” vs. “pro” vaccine. Vaccines 9, 1428 (2021).
Brunelli, L. et al. Parental trust and beliefs after the discovery of a six-year-long failure to vaccinate. Hum. Vaccin. Immunother. 17, 583–587 (2020).
Armiento, R. et al. Impact of Australian mandatory ‘No Jab, No Pay’ and ‘No Jab, No Play’ immunisation policies on immunisation services, parental attitudes to vaccination and vaccine uptake, in a tertiary paediatric hospital, the Royal Children’s Hospital, Melbourne. Vaccine 38, 5231–5240 (2020).
Berry, N. J. et al. Sharing knowledge about immunisation (SKAI): an exploration of parents’ communication needs to inform development of a clinical communication support intervention. Vaccine 36, 6480–6490 (2018).
Bocquier, A. et al. Social differentiation of vaccine hesitancy among French parents and the mediating role of trust and commitment to health: a nationwide cross-sectional study. Vaccine 36, 7666–7673 (2018).
Chang, K. & Lee, S. Y. Why do some Korean parents hesitate to vaccinate their children? Epidemiol. Health 41, e2019031 (2019).
Danchin, M. H. et al. Vaccine decision-making begins in pregnancy: correlation between vaccine concerns, intentions and maternal vaccination with subsequent childhood vaccine uptake. Vaccine 36, 6473–6479 (2018).
Forbes, T. A., McMinn, A., Crawford, N., Leask, J. & Danchin, M. Vaccination uptake by vaccine-hesitant parents attending a specialist immunization clinic in Australia. Hum. Vaccin. Immunother. 11, 2895–2903 (2015).
Glanternik, J. R. et al. Evaluation of a vaccine-communication tool for physicians. J. Pediatr. 224, 72–78.e1 (2020).
McDonald, P. et al. Exploring California’s new law eliminating personal belief exemptions to childhood vaccines and vaccine decision-making among homeschooling mothers in California. Vaccine 37, 742–750 (2019).
Noyman-Veksler, G., Greenberg, D., Grotto, I. & Shahar, G. Parents’ malevolent personification of mass vaccination solidifies vaccine hesitancy. J. Health Psychol. https://doi.org/10.1177/1359105320903475 (2020).
Duong, M. C., Nguyen, H. T. & Duong, M. Evaluating COVID-19 vaccine hesitancy: a qualitative study from Vietnam. Diabetes Metab. Syndr. 16, 102363 (2022).
Gatto, N. M. et al. Correlates of COVID-19 vaccine acceptance, hesitancy and refusal among employees of a safety net California County health system with an early and aggressive vaccination program: results from a cross-sectional survey. Vaccines 9, 1152 (2021).
Moore, J. X. et al. Correlates of COVID-19 vaccine hesitancy among a community sample of African Americans living in the southern United States. Vaccines 9, 879 (2021).
Murphy, J. et al. Psychological characteristics associated with COVID-19 vaccine hesitancy and resistance in Ireland and the United Kingdom. Nat. Commun. 12, 29 (2021).
Musa, S. et al. A qualitative interview study with parents to identify barriers and drivers to childhood vaccination and inform public health interventions. Hum. Vaccin. Immunother. 17, 3023–3033 (2021).
Steffens, M. S., Bullivant, B., Bolsewicz, K. T., King, C. & Beard, F. “to protect myself, my friends, family, workmates and patients… and to play my part”: COVID-19 vaccination perceptions among health and aged care workers in New South Wales, Australia. Int. J. Environ. Res. Public Health 18, 8954 (2021).
Tavolacci, M. P., Dechelotte, P. & Ladner, J. COVID-19 vaccine acceptance, hesitancy, and resistancy among university students in France. Vaccines 9, 654 (2021).
Buttenheim, A. M. et al. Vaccine exemption requirements and parental vaccine attitudes: an online experiment. Vaccine 38, 2620–2625 (2020).
Corben, P. & Leask, J. Vaccination hesitancy in the antenatal period: a cross-sectional survey. BMC Public Health 18, 566 (2018).
Gagneur, A. et al. Promoting vaccination in maternity wards ─ motivational interview technique reduces hesitancy and enhances intention to vaccinate, results from a multicentre non-controlled pre- and post-intervention RCT-nested study, Quebec, March 2014 to February 2015. Eur. Surveill. 24, 1800641 (2019).
Lau, L. H. W., Lee, S. S. & Wong, N. S. The continuum of influenza vaccine hesitancy among nursing professionals in Hong Kong. Vaccine 38, 6785–6793 (2020).
Nekrasova, E. et al. Vaccine hesitancy and influenza beliefs among parents of children requiring a second dose of influenza vaccine in a season: an American Academy of Pediatrics (AAP) Pediatric Research in Office Settings (PROS) study. Hum. Vaccin. Immunother. 16, 1070–1077 (2020).
Verger, P. et al. Prevalence and correlates of vaccine hesitancy among general practitioners: a cross-sectional telephone survey in France, April to July 2014. Eur. Surveill. 21, 30406 (2016).
Bianco, A. et al. Parental COVID-19 vaccine hesitancy: a cross-sectional survey in Italy. Expert Rev. Vaccines 21, 541–547 (2022).
Edwards, B., Biddle, N., Gray, M. & Sollis, K. COVID-19 vaccine hesitancy and resistance: correlates in a nationally representative longitudinal survey of the Australian population. PLoS ONE 16, e0248892 (2021).
Hsieh, Y. L., Rak, S., SteelFisher, G. K. & Bauhoff, S. Effect of the suspension of the J&J COVID-19 vaccine on vaccine hesitancy in the United States. Vaccine 40, 424–427 (2022).
Umakanthan, S., Patil, S., Subramaniam, N. & Sharma, R. COVID-19 vaccine hesitancy and resistance in India explored through a population-based longitudinal survey. Vaccines 9, 1064 (2021).
Zheng, W. et al. COVID-19 vaccine uptake and hesitancy among HIV-infected men who have sex with men in mainland China: a cross-sectional survey. Hum. Vaccin. Immunother. 17, 4971–4981 (2021).
Baniak, L. M., Luyster, F. S., Raible, C. A., McCray, E. E. & Strollo, P. J. COVID-19 vaccine hesitancy and uptake among nursing staff during an active vaccine rollout. Vaccines 9, 858 (2021).
Bou Hamdan, M., Singh, S., Polavarapu, M., Jordan, T. R. & Melhem, N. M. COVID-19 vaccine hesitancy among university students in Lebanon. Epidemiol. Infect. 149, e242 (2021).
Castellano-Tejedor, C., Torres-Serrano, M. & Cencerrado, A. Unveiling Associations of COVID-19 vaccine acceptance, hesitancy, and resistance: a cross-sectional community-based adult survey. Int. J. Environ. Res. Public Health 18, 12348 (2021).
Freeman, D. et al. Effects of different types of written vaccination information on COVID-19 vaccine hesitancy in the UK (OCEANS-III): a single-blind, parallel-group, randomised controlled trial. Lancet Public Health 6, e416–e427 (2021).
Janssen, C. et al. Hesitancy towards COVID-19 vaccination among healthcare workers: a multi-centric survey in France. Vaccines 9, 547 (2021).
Khaled, S. M. et al. Prevalence and potential determinants of COVID-19 vaccine hesitancy and resistance in Qatar: results from a nationally representative survey of Qatari nationals and migrants between December 2020 and January 2021. Vaccines 9, 471 (2021).
Montagni, I. et al. Acceptance of a Covid-19 vaccine is associated with ability to detect fake news and health literacy. J. Public Health https://doi.org/10.1093/pubmed/fdab028 (2021).
Qunaibi, E., Basheti, I., Soudy, M. & Sultan, I. Hesitancy of Arab healthcare workers towards COVID-19 vaccination: a large-scale multinational study. Vaccines 9, 446 (2021).
Reno, C. et al. Enhancing COVID-19 vaccines acceptance: results from a survey on vaccine hesitancy in northern Italy. Vaccines 9, 378 (2021).
Rodríguez-Blanco, N. et al. Willingness to be vaccinated against COVID-19 in Spain before the start of vaccination: a cross-sectional study. Int. J. Environ. Res. Public Health 18, 5272 (2021).
Leung, C. L. K. et al. Profiling vaccine believers and skeptics in nurses: a latent profile analysis. Int. J. Nurs. Stud. 126, 104142 (2021).
Salerno, L., Craxì, L., Amodio, E. & Lo Coco, G. Factors affecting hesitancy to mRNA and viral vector COVID-19 vaccines among college students in Italy. Vaccines 9, 927 (2021).
Zona, S. et al. Anti-COVID vaccination for adolescents: a survey on determinants of vaccine parental hesitancy. Vaccines 9, 1309 (2021).
Alabbad, A. A., Alsaad, A. K., Al Shaalan, M. A., Alola, S. & Albanyan, E. A. Prevalence of influenza vaccine hesitancy at a tertiary care hospital in Riyadh, Saudi Arabia. J. Infect. Public Health 11, 491–499 (2018).
Barello, S., Nania, T., Dellafiore, F., Graffigna, G. & Caruso, R. ‘Vaccine hesitancy’ among university students in Italy during the COVID-19 pandemic. Eur. J. Epidemiol. 35, 781–783 (2020).
Bogart, L. M. et al. COVID-19 related medical mistrust, health impacts, and potential vaccine hesitancy among Black Americans living with HIV. J. Acquir. Immune Defic. Syndr. 86, 200–207 (2020).
Brown, A. L. et al. Vaccine confidence and hesitancy in Brazil. Cad. Saude Publica 34, e00011618 (2018).
Byström, E., Lindstrand, A., Bergström, J., Riesbeck, K. & Roth, A. Confidence in the National Immunization Program among parents in Sweden 2016 – a cross-sectional survey. Vaccine 38, 3909–3917 (2020).
Costantino, C. et al. Determinants of vaccine hesitancy and effectiveness of vaccination counseling interventions among a sample of the general population in Palermo, Italy. Hum. Vaccin. Immunother. 16, 2415–2421 (2020).
Deas, J., Bean, S. J., Sokolovska, I. & Fautin, C. Childhood vaccine attitudes and information sources among Oregon parents and guardians. Health Promot. Pract. 20, 529–538 (2019).
Dempsey, A. F., Pyrzanowski, J., Campagna, E. J., Lockhart, S. & O’Leary, S. T. Parent report of provider HPV vaccine communication strategies used during a randomized, controlled trial of a provider communication intervention. Vaccine 37, 1307–1312 (2019).
Detoc, M. et al. Intention to participate in a COVID-19 vaccine clinical trial and to get vaccinated against COVID-19 in France during the pandemic. Vaccine 38, 7002–7006 (2020).
Du, F. et al. The determinants of vaccine hesitancy in China: a cross-sectional study following the Changchun Changsheng vaccine incident. Vaccine 38, 7464–7471 (2020).
Dubé, E., Gagnon, D., Zhou, Z. & Deceuninck, G. Parental vaccine hesitancy in Quebec (Canada). PLoS Curr. https://doi.org/10.1371/currents.outbreaks.9e239605f4d320c6ad27ce2aea5aaad2 (2016).
Fisher, K. A. et al. Attitudes toward a potential SARS-CoV-2 vaccine: a survey of U.S. adults. Ann. Intern. Med. 173, 964–973 (2020).
Gesser-Edelsburg, A., Walter, N., Shir-Raz, Y., Sassoni Bar-Lev, O. & Rosenblat, S. The behind-the-scenes activity of parental decision-making discourse regarding childhood vaccination. Am. J. Infect. Control 45, 267–271 (2017).
Gowda, C., Schaffer, S. E., Kopec, K., Markel, A. & Dempsey, A. F. A pilot study on the effects of individually tailored education for MMR vaccine-hesitant parents on MMR vaccination intention. Hum. Vaccin. Immunother. 9, 437–445 (2013).
Gowda, C., Schaffer, S. E., Kopec, K., Markel, A. & Dempsey, A. F. Does the relative importance of MMR vaccine concerns differ by degree of parental vaccine hesitancy?: an exploratory study. Hum. Vaccin. Immunother. 9, 430–436 (2013).
Hadjipanayis, A. et al. Vaccine confidence among parents: large scale study in eighteen European countries. Vaccine 38, 1505–1512 (2020).
Hirth, J. M., Fuchs, E. L., Chang, M., Fernandez, M. E. & Berenson, A. B. Variations in reason for intention not to vaccinate across time, region, and by race/ethnicity, NIS-Teen (2008–2016). Vaccine 37, 595–601 (2019).
Karlsson, L. C. et al. The association between vaccination confidence, vaccination behavior, and willingness to recommend vaccines among Finnish healthcare workers. PLoS ONE 14, e0224330 (2019).
Khodadadi, A. B., Redden, D. T. & Scarinci, I. C. HPV vaccination hesitancy among latina immigrant mothers despite physician recommendation. Ethn. Dis. 30, 661–670 (2020).
Melot, B. et al. Knowledge, attitudes and practices about vaccination in Trentino, Italy in 2019. Hum. Vaccin. Immunother. 17, 259–268 (2020).
Mereu, N. et al. Vaccination attitude and communication in early settings: an exploratory study. Vaccines 8, 701 (2020).
Opel, D. J. et al. Characterizing providers’ immunization communication practices during health supervision visits with vaccine-hesitant parents: a pilot study. Vaccine 30, 1269–1275 (2012).
Özceylan, G., Toprak, D. & Esen, E. S. Vaccine rejection and hesitation in Turkey. Hum. Vaccin. Immunother. 16, 1034–1039 (2020).
Pahud, B. et al. A randomized controlled trial of an online immunization curriculum. Vaccine 38, 7299–7307 (2020).
Quinn, S. C. et al. Breaking down the monolith: understanding flu vaccine uptake among African Americans. SSM Popul. Health 4, 25–36 (2018).
Quinn, S. C. et al. Exploring racial influences on flu vaccine attitudes and behavior: results of a national survey of White and African American adults. Vaccine 35, 1167–1174 (2017).
Quinn, S. C., Jamison, A. M., An, J., Hancock, G. R. & Freimuth, V. S. Measuring vaccine hesitancy, confidence, trust and flu vaccine uptake: results of a national survey of White and African American adults. Vaccine 37, 1168–1173 (2019).
Repalust, A., Šević, S., Rihtar, S. & Štulhofer, A. Childhood vaccine refusal and hesitancy intentions in Croatia: insights from a population-based study. Psychol. Health Med. 22, 1045–1055 (2017).
Rey, D. et al. Vaccine hesitancy in the French population in 2016, and its association with vaccine uptake and perceived vaccine risk-benefit balance. Eur. Surveill. 23, 17–00816 (2018).
Santibanez, T. A. et al. Parental vaccine hesitancy and childhood influenza vaccination. Pediatrics 146, e2020007609 (2020).
Schollin Ask, L. et al. Receiving early information and trusting Swedish child health centre nurses increased parents’ willingness to vaccinate against rotavirus infections. Acta Paediatr. 106, 1309–1316 (2017).
Suryadevara, M., Handel, A., Bonville, C. A., Cibula, D. A. & Domachowske, J. B. Pediatric provider vaccine hesitancy: an under-recognized obstacle to immunizing children. Vaccine 33, 6629–6634 (2015).
Taylor, S. et al. A proactive approach for managing COVID-19: the importance of understanding the motivational roots of vaccination hesitancy for SARS-CoV2. Front. Psychol. 11, 575950 (2020).
Tran, B. X. et al. Media representation of vaccine side effects and its impact on utilization of vaccination services in Vietnam. Patient Prefer. Adherence 12, 1717–1728 (2018).
Wilson, R. et al. Vaccine hesitancy and self-vaccination behaviors among nurses in southeastern France. Vaccine 38, 1144–1151 (2020).
Yu, W. et al. Two media-reported vaccine events in China from 2013 to 2016: impact on confidence and vaccine utilization. Vaccine 38, 5541–5547 (2020).
Abdel-Qader, D. H. et al. Pharmacists-physicians collaborative intervention to reduce vaccine hesitancy and resistance: a randomized controlled trial. Vaccine X 10, 100135 (2022).
Abedin, M. et al. Willingness to vaccinate against COVID-19 among Bangladeshi adults: understanding the strategies to optimize vaccination coverage. PLoS ONE 16, e0250495 (2021).
Abou Leila, R., Salamah, M. & El-Nigoumi, S. Reducing COVID-19 vaccine hesitancy by implementing organizational intervention in a primary care setting in Bahrain. Cureus 13, e19282 (2021).
Aguilar Ticona, J. P. et al. Willingness to get the COVID-19 vaccine among residents of slum settlements. Vaccines 9, 951 (2021).
Ahmad, K. K. Coronavirus disease 2019 vaccine hesitancy in the Kurdistan region: a cross-sectional national survey. Arch. Razi Inst. 76, 751–759 (2021).
Al-Ayyadhi, N., Ramadan, M. M., Al-Tayar, E., Al-Mathkouri, R. & Al-Awadhi, S. Determinants of hesitancy towards COVID-19 vaccines in State of Kuwait: an exploratory internet-based survey. Risk Manage. Healthc. Policy 14, 4967–4981 (2021).
Alfieri, N. L. et al. Parental COVID-19 vaccine hesitancy for children: vulnerability in an urban hotspot. BMC Public Health 21, 1662 (2021).
Alibrahim, J. & Awad, A. COVID-19 vaccine hesitancy among the public in Kuwait: a cross-sectional survey. Int. J. Environ. Res. Public Health 18, 8836 (2021).
Allington, D., McAndrew, S., Moxham-Hall, V. & Duffy, B. Coronavirus conspiracy suspicions, general vaccine attitudes, trust and coronavirus information source as predictors of vaccine hesitancy among UK residents during the COVID-19 pandemic. Psychol. Med. https://doi.org/10.1017/s0033291721001434 (2021).
Al-Sanafi, M. & Sallam, M. Psychological determinants of COVID-19 vaccine acceptance among healthcare workers in Kuwait: a cross-sectional study using the 5C and vaccine conspiracy beliefs scales. Vaccines 9, 701 (2021).
Alshahrani, S. M. et al. Acceptability of COVID-19 vaccination in Saudi Arabia: a cross-sectional study using a web-based survey. Hum. Vaccin. Immunother. 17, 3338–3347 (2021).
Al-Wutayd, O., Khalil, R. & Rajar, A. B. Sociodemographic and behavioral predictors of COVID-19 vaccine hesitancy in Pakistan. J. Multidiscip. Healthc. 14, 2847–2856 (2021).
Alzeer, A. A. et al. The influence of demographics on influenza vaccine awareness and hesitancy among adults visiting educational hospital in Saudi Arabia. Saudi Pharm. J. 29, 188–193 (2021).
Alzubaidi, H. et al. A mixed-methods study to assess COVID-19 vaccination acceptability among university students in the United Arab Emirates. Hum. Vaccin. Immunother. 17, 4074–4082 (2021).
Anandraj, J., Krishnamoorthy, Y., Sivanantham, P., Gnanadas, J. & Kar, S. S. Impact of second wave of COVID-19 pandemic on the hesitancy and refusal of COVID-19 vaccination in Puducherry, India: a longitudinal study. Hum. Vaccin. Immunother. 17, 5024–5029 (2021).
Arvanitis, M. et al. Factors associated with COVID-19 vaccine trust and hesitancy among adults with chronic conditions. Prev. Med. Rep. 24, 101484 (2021).
Baccolini, V. et al. COVID-19 vaccine hesitancy among Italian university students: a cross-sectional survey during the first months of the vaccination campaign. Vaccines 9, 1292 (2021).
Bacon, A. M. & Taylor, S. Vaccination hesitancy and conspiracy beliefs in the UK During the SARS-COV-2 (COVID-19) pandemic. Int. J. Behav. Med. 29, 448–455 (2022).
Badr, H. et al. Overcoming COVID-19 vaccine hesitancy: insights from an online population-based survey in the United States. Vaccines 9, 1100 (2021).
Batty, G. D., Deary, I. J., Fawns-Ritchie, C., Gale, C. R. & Altschul, D. Pre-pandemic cognitive function and COVID-19 vaccine hesitancy: cohort study. Brain Behav. Immun. 96, 100–105 (2021).
Benham, J. L. et al. COVID-19 vaccine-related attitudes and beliefs in Canada: national cross-sectional survey and cluster analysis. JMIR Public Health Surveill. 7, e30424 (2021).
Bolatov, A. K., Seisembekov, T. Z., Askarova, A. Z. & Pavalkis, D. Barriers to COVID-19 vaccination among medical students in Kazakhstan: development, validation, and use of a new COVID-19 vaccine hesitancy scale. Hum. Vaccin. Immunother. 17, 4982–4992 (2021).
Butter, S., McGlinchey, E., Berry, E. & Armour, C. Psychological, social, and situational factors associated with COVID-19 vaccination intentions: A study of UK key workers and non-key workers. Br. J. Health Psychol. 27, 13–29 (2022).
Chandani, S. et al. COVID-19 vaccination hesitancy in India: state of the nation and priorities for research. Brain Behav. Immun. Health 18, 100375 (2021).
Chaudhary, F. A. et al. Factors influencing COVID-19 vaccine hesitancy and acceptance among the Pakistani population. Hum. Vaccin. Immunother. 17, 3365–3370 (2021).
Chen, H. et al. Health belief model perspective on the control of COVID-19 vaccine hesitancy and the promotion of vaccination in China: web-based cross-sectional study. J. Med. Internet Res. 23, e29329 (2021).
Cherian, V., Saini, N. K., Sharma, A. K. & Philip, J. Prevalence and predictors of vaccine hesitancy in an urbanized agglomeration of New Delhi, India. J. Public Health 44, 70–76 (2022).
Contoli, B. et al. What is the willingness to receive vaccination against COVID-19 among the elderly in Italy? Data from the PASSI d’Argento surveillance system. Front. Public Health 9, 736976 (2021).
Cordina, M., Lauri, M. A. & Lauri, J. Attitudes towards COVID-19 vaccination, vaccine hesitancy and intention to take the vaccine. Pharm. Pract. 19, 2317 (2021).
Costantino, A. et al. COVID-19 vaccine acceptance among liver transplant recipients. Vaccines 9, 1314 (2021).
Costantino, A. et al. COVID-19 vaccine: a survey of hesitancy in patients with celiac disease. Vaccines 9, 511 (2021).
Coughenour, C., Gakh, M., Sharma, M., Labus, B. & Chien, L. C. Assessing determinants of COVID-19 vaccine hesitancy in Nevada. Health Secur. 19, 592–604 (2021).
Crane, M. A., Faden, R. R. & Romley, J. A. Disparities in county COVID-19 vaccination rates linked to disadvantage and hesitancy. Health Aff. 40, 1792–1796 (2021).
Danabal, K. G. M., Magesh, S. S., Saravanan, S. & Gopichandran, V. Attitude towards COVID 19 vaccines and vaccine hesitancy in urban and rural communities in Tamil Nadu, India - a community based survey. BMC Health Serv. Res. 21, 994 (2021).
Doherty, I. A. et al. COVID-19 vaccine hesitancy in underserved communities of North Carolina. PLoS ONE 16, e0248542 (2021).
Du, F. et al. Access to vaccination information and confidence/hesitancy towards childhood vaccination: a cross-sectional survey in China. Vaccines 9, 201 (2021).
Du, M., Tao, L. & Liu, J. The association between risk perception and COVID-19 vaccine hesitancy for children among reproductive women in China: an online survey. Front. Med. 8, 741298 (2021).
Ebrahimi, O. V. et al. Risk, trust, and flawed assumptions: vaccine hesitancy during the COVID-19 pandemic. Front. Public Health 9, 700213 (2021).
Ehde, D. M., Roberts, M. K., Humbert, A. T., Herring, T. E. & Alschuler, K. N. COVID-19 vaccine hesitancy in adults with multiple sclerosis in the United States: a follow up survey during the initial vaccine rollout in 2021. Mult. Scler. Relat. Disord. 54, 103163 (2021).
Ekstrand, M. L. et al. COVID-19 vaccine hesitancy among PLWH in South India: implications for vaccination campaigns. J. Acquir. Immune Defic. Syndr. 88, 421–425 (2021).
Elizondo-Alzola, U. et al. Vaccine hesitancy among paediatric nurses: prevalence and associated factors. PLoS ONE 16, e0251735 (2021).
Emerson, E. et al. Vaccine hesitancy among working-age adults with/without disability in the UK. Public Health 200, 106–108 (2021).
Epstein, S. et al. Vaccination Against SARS-CoV-2 in neuroinflammatory disease: early safety/tolerability data. Mult. Scler. Relat. Disord. 57, 103433 (2021).
Eyllon, M. et al. Associations between psychiatric morbidity and COVID-19 vaccine hesitancy: an analysis of electronic health records and patient survey. Psychiatry Res. 307, 114329 (2022).
Fares, S., Elmnyer, M. M., Mohamed, S. S. & Elsayed, R. COVID-19 vaccination perception and attitude among healthcare workers in Egypt. J. Prim. Care Community Health 12, 21501327211013303 (2021).
Fayed, A. A. et al. Willingness to receive the COVID-19 and seasonal influenza vaccines among the Saudi population and vaccine uptake during the initial stage of the national vaccination campaign: a cross-sectional survey. Vaccines 9, 765 (2021).
Fazel, M. et al. Willingness of children and adolescents to have a COVID-19 vaccination: results of a large whole schools survey in England. eClinicalMedicine 40, 101144 (2021).
Fernández-Penny, F. E. et al. COVID-19 vaccine hesitancy among patients in two urban emergency departments. Acad. Emerg. Med. 28, 1100–1107 (2021).
Fisher, K. A. et al. Preferences for COVID-19 vaccination information and location: associations with vaccine hesitancy, race and ethnicity. Vaccine 39, 6591–6594 (2021).
Gatwood, J., McKnight, M., Fiscus, M., Hohmeier, K. C. & Chisholm-Burns, M. Factors influencing likelihood of COVID-19 vaccination: a survey of Tennessee adults. Am. J. Health Syst. Pharm. 78, 879–889 (2021).
Gbeasor-Komlanvi, F. A. et al. Prevalence and factors associated with COVID-19 vaccine hesitancy in health professionals in Togo, 2021. Public Health Pract. 2, 100220 (2021).
Gendler, Y. & Ofri, L. Investigating the influence of vaccine literacy, vaccine perception and vaccine hesitancy on Israeli parents’ acceptance of the COVID-19 vaccine for their children: a cross-sectional study. Vaccines 9 (2021).
Gentile, A. et al. Vaccine hesitancy in Argentina: validation of WHO scale for parents. Vaccine 39, 4611–4619 (2021).
Gerretsen, P. et al. Individual determinants of COVID-19 vaccine hesitancy. PLoS ONE 16, e0258462 (2021).
Gerretsen, P. et al. Vaccine hesitancy is a barrier to achieving equitable herd immunity among racial minorities. Front. Med. 8, 668299 (2021).
Griva, K. et al. Evaluating rRates and determinants of COVID-19 vaccine hesitancy for adults and children in the Singapore population: Strengthening Our Community’s Resilience against Threats from Emerging Infections (SOCRATEs) Cohort. Vaccines 9, 1415 (2021).
Guaraldi, F. et al. Rate and predictors of hesitancy toward SARS-CoV-2 vaccine among type 2 diabetic patients: results from an Italian survey. Vaccines 9, 460 (2021).
Hara, M., Ishibashi, M., Nakane, A., Nakano, T. & Hirota, Y. Differences in COVID-19 vaccine acceptance, hesitancy, and confidence between healthcare workers and the general population in Japan. Vaccines 9, 1389 (2021).
Holeva, V., Parlapani, E., Nikopoulou, V. A., Nouskas, I. & Diakogiannis, I. COVID-19 vaccine hesitancy in a sample of Greek adults. Psychol. Health Med. 27, 113–119 (2022).
Hong, J. et al. Knowledge about, attitude and acceptance towards, and predictors of intention to receive the COVID-19 vaccine among cancer patients in eastern China: a cross-sectional survey. J. Integr. Med. 20, 34–44 (2021).
Hossain, M. B. et al. COVID-19 vaccine hesitancy among the adult population in Bangladesh: a nationwide cross-sectional survey. PLoS ONE 16, e0260821 (2021).
Hossain, M. B. et al. Health belief model, theory of planned behavior, or psychological antecedents: what predicts covid-19 vaccine hesitancy better among the Bangladeshi adults? Front. Public Health 9, 711066 (2021).
Huang, H. et al. COVID-19 vaccine uptake, acceptance, and hesitancy among persons with mental disorders during the second stage of China’s nationwide vaccine rollout. Front. Med. 8, 761601 (2021).
Hussain, S. et al. Perceptions regarding COVID-19 vaccination among a representative Pakistani population coming to tertiary care cardiac hospital. Cureus 13, e18654 (2021).
Hwang, S. E., Kim, W. H. & Heo, J. Socio-demographic, psychological, and experiential predictors of COVID-19 vaccine hesitancy in South Korea, October–December 2020. Hum. Vaccin. Immunother. 18, 1–8 (2021).
Hyland, P. et al. Detecting and describing stability and change in COVID-19 vaccine receptibility in the United Kingdom and Ireland. PLoS ONE 16, e0258871 (2021).
Issanov, A., Akhmetzhanova, Z., Riethmacher, D. & Aljofan, M. Knowledge, attitude, and practice toward COVID-19 vaccination in Kazakhstan: a cross-sectional study. Hum. Vaccin. Immunother. 17, 3394–3400 (2021).
Jain, J. et al. COVID-19 vaccine hesitancy among medical students in India. Epidemiol. Infect. 149, e132 (2021).
Kanyike, A. M. et al. Acceptance of the coronavirus disease-2019 vaccine among medical students in Uganda. Trop. Med. Health 49, 37 (2021).
Kateeb, E. et al. Predictors of willingness to receive COVID-19 vaccine: cross-sectional study of Palestinian dental students. Vaccines 9, 954 (2021).
Khairat, S., Zou, B. & Adler-Milstein, J. Factors and reasons associated with low COVID-19 vaccine uptake among highly hesitant communities in the US. Am. J. Infect. Control 50, 262–267 (2022).
Khan, M. S. R., Watanapongvanich, S. & Kadoya, Y. COVID-19 vaccine hesitancy among the younger generation in Japan. Int. J. Environ. Res. Public Health 18, 11702 (2021).
Khodadadi, A. B., Hansen, B., Kim, Y. I. & Scarinci, I. C. Latinx immigrant mothers’ perceived self-efficacy and intentions regarding human papillomavirus vaccination of their daughters. Womens Health Issues 32, 293–300 (2022).
King, W. C., Rubinstein, M., Reinhart, A. & Mejia, R. Time trends, factors associated with, and reasons for COVID-19 vaccine hesitancy: a massive online survey of US adults from January–May 2021. PLoS ONE 16, e0260731 (2021).
King, W. C., Rubinstein, M., Reinhart, A. & Mejia, R. COVID-19 vaccine hesitancy January–May 2021 among 18–64 year old US adults by employment and occupation. Prev. Med. Rep. 24, 101569 (2021).
Ko, T., Dendle, C., Woolley, I., Morand, E. & Antony, A. SARS-COV-2 vaccine acceptance in patients with rheumatic diseases: a cross-sectional study. Hum. Vaccin. Immunother. 17, 4048–4056 (2021).
Kollamparambil, U., Oyenubi, A. & Nwosu, C. COVID19 vaccine intentions in South Africa: health communication strategy to address vaccine hesitancy. BMC Public Health 21, 2113 (2021).
Kozak, A. & Nienhaus, A. COVID-19 vaccination: status and willingness to be vaccinated among employees in health and welfare care in Germany. Int. J. Environ. Res. Public Health 18, 6688 (2021).
Krishnamurthy, K. et al. COVID-19 vaccine intent among health care professionals of Queen Elizabeth Hospital, Barbados. J. Multidiscip. Healthc. 14, 3309–3319 (2021).
Ku, L. The association of social factors and health insurance coverage with COVID-19 vaccinations and hesitancy, July 2021. J. Gen. Intern. Med. 37, 409–414 (2022).
Kuhn, R. et al. COVID-19 vaccine access and attitudes among people experiencing homelessness from pilot mobile phone survey in Los Angeles, CA. PLoS ONE 16, e0255246 (2021).
Kumar, R., Alabdulla, M., Elhassan, N. M. & Reagu, S. M. Qatar healthcare workers’ COVID-19 vaccine hesitancy and attitudes: a national cross-sectional survey. Front. Public Health 9, 727748 (2021).
Lang, R. et al. COVID-19 vaccine attitudes and beliefs: a Canadian national cross-sectional survey and cluster analysis. JMIR Public Health Surveill. 7, e30424 (2021).
Lee, M. & You, M. Direct and indirect associations of media use with COVID-19 vaccine hesitancy in South Korea: cross-sectional web-based survey. J. Med. Internet Res. 24, e32329 (2022).
Li, M. et al. Hesitancy toward COVID-19 vaccines among medical students in Southwest China: a cross-sectional study. Hum. Vaccin. Immunother. 17, 4021–4027 (2021).
Liddell, B. J. et al. Factors associated with COVID-19 vaccine hesitancy amongst refugees in Australia. Eur. J. Psychotraumatol. 12, 1997173 (2021).
Lim, L. J., Lim, A. J. W., Fong, K. K. & Lee, C. G. Sentiments regarding COVID-19 vaccination among graduate students in Singapore. Vaccines 9, 1141 (2021).
Liu, R. & Li, G. M. Hesitancy in the time of coronavirus: temporal, spatial, and sociodemographic variations in COVID-19 vaccine hesitancy. SSM Popul. Health 15, 100896 (2021).
Longchamps, C. et al. COVID-19 vaccine hesitancy among persons living in homeless shelters in France. Vaccine 39, 3315–3318 (2021).
Luk, T. T. et al. Prevalence and determinants of SARS-CoV-2 vaccine hesitancy in Hong Kong: a population-based survey. Vaccine 39, 3602–3607 (2021).
Luo, H. et al. Willingness to get a COVID-19 vaccine and reasons for hesitancy among medicare beneficiaries: results from a national survey. J. Public Health Manage. Pract. 28, 70–76 (2022).
Magon, A. et al. The effect of health literacy on vaccine hesitancy among Italian anticoagulated population during COVID-19 pandemic: the moderating role of health engagement. Hum. Vaccin. Immunother. 17, 5007–5012 (2021).
Martinelli, M. & Veltri, G. A. Do cognitive styles affect vaccine hesitancy? A dual-process cognitive framework for vaccine hesitancy and the role of risk perceptions. Soc. Sci. Med. 289, 114403 (2021).
McCabe, S. D. et al. Unraveling Attributes of COVID-19 vaccine hesitancy and uptake in the U.S.: a large nationwide study. Preprint at medRxiv https://doi.org/10.1101/2021.04.05.21254918 (2021).
McCarthy, M., Murphy, K., Sargeant, E. & Williamson, H. Examining the relationship between conspiracy theories and covid-19 vaccine hesitancy: a mediating role for perceived health threats, trust, and anomie? Anal. Soc. Issues Public Policy 22, 106–129 (2022).
McElfish, P. A. et al. Sociodemographic determinants of COVID-19 vaccine hesitancy, fear of infection, and protection self-efficacy. J. Prim. Care Community Health 12, 21501327211040746 (2021).
Milošević Đorđević, J., Mari, S., Vdović, M. & Milošević, A. Links between conspiracy beliefs, vaccine knowledge, and trust: anti-vaccine behavior of Serbian adults. Soc. Sci. Med. 277, 113930 (2021).
Mohamad, O. et al. Factors associated with the intention of Syrian adult population to accept COVID19 vaccination: a cross-sectional study. BMC Public Health 21, 1310 (2021).
Mohan, S., Reagu, S., Lindow, S. & Alabdulla, M. COVID-19 vaccine hesitancy in perinatal women: a cross sectional survey. J. Perinat. Med. 49, 678–685 (2021).
Mohanan, L., Klugar, M., Pokorna, A. & Riad, A. COVID-19 vaccine booster hesitancy (VBH) of healthcare workers in Czechia: national cross-sectional study. Vaccines 9, 1437 (2021).
Momplaisir, F. M. et al. Racial/ethnic differences in COVID-19 vaccine hesitancy among health care workers in 2 large academic hospitals. JAMA Netw. Open 4, e2121931 (2021).
Monami, M. et al. COVID-19 vaccine hesitancy and early adverse events reported in a cohort of 7,881 Italian physicians. Ann. Ig. 34, 344–357 (2022).
Moore, D. et al. Low COVID-19 vaccine hesitancy in Brazil. Vaccine 39, 6262–6268 (2021).
Morris, J. L., Baniak, L. M., Luyster, F. S. & Dunbar-Jacob, J. Covid-19 vaccine confidence and hesitancy in nursing students and faculty at a large academic medical center. Nurs. Outlook 70, 347–354 (2022).
Muhajarine, N. et al. COVID-19 vaccine hesitancy and refusal and associated factors in an adult population in Saskatchewan, Canada: evidence from predictive modelling. PLoS ONE 16, e0259513 (2021).
Myers, A., Ipsen, C. & Lissau, A. COVID-19 vaccination hesitancy among Americans with disabilities aged 18-65: An exploratory analysis. Disabil. Health J. 15, 101223 (2022).
Nowak, S. A., Gidengil, C. A., Parker, A. M. & Matthews, L. J. Association among trust in health care providers, friends, and family, and vaccine hesitancy. Vaccine 39, 5737–5740 (2021).
Okubo, R., Yoshioka, T., Ohfuji, S., Matsuo, T. & Tabuchi, T. COVID-19 vaccine hesitancy and its associated factors in Japan. Vaccines 9, 662 (2021).
Oliveira, B. et al. Prevalence and factors associated with covid-19 vaccine hesitancy in Maranhão, Brazil. Rev. Saude Publica 55, 12 (2021).
Omar, D. I. & Hani, B. M. Attitudes and intentions towards COVID-19 vaccines and associated factors among Egyptian adults. J. Infect. Public Health 14, 1481–1488 (2021).
Orangi, S. et al. Assessing the level and determinants of COVID-19 vaccine confidence in Kenya. Vaccines 9, 936 (2021).
Pal, S. et al. COVID-19 vaccine hesitancy and attitude toward booster doses among US healthcare workers. Vaccines 9, 1358 (2021).
Park, H. K., Ham, J. H., Jang, D. H., Lee, J. Y. & Jang, W. M. Political ideologies, government trust, and COVID-19 vaccine hesitancy in South Korea: a cross-sectional survey. Int. J. Environ. Res. Public Health 18, 10655 (2021).
Piltch-Loeb, R. et al. COVID-19 vaccine concerns about safety, effectiveness, and policies in the United States, Canada, Sweden, and Italy among unvaccinated individuals. Vaccines 9, 1138 (2021).
Purnell, M. et al. Exploring COVID-19 vaccine hesitancy at a rural historically black college and university. J. Am. Pharm. Assoc. 62, 340–344 (2021).
Purvis, R. S. et al. Trusted sources of COVID-19 vaccine information among hesitant adopters in the United States. Vaccines 9, 1418 (2021).
Qunaibi, E. A., Helmy, M., Basheti, I. & Sultan, I. A high rate of COVID-19 vaccine hesitancy in a large-scale survey on Arabs. eLife 10, e68038 (2021).
Riad, A. et al. Prevalence and drivers of COVID-19 vaccine hesitancy among Czech university students: national cross-sectional study. Vaccines 9, 948 (2021).
Lavoie, K. et al. Understanding national trends in COVID-19 vaccine hesitancy in Canada - April 2020 to March 2021. BMJ Open 12, e059411 (2022).
Robertson, E. et al. Predictors of COVID-19 vaccine hesitancy in the UK household longitudinal study. Brain Behav. Immun. 94, 41–50 (2021).
Rodriguez, R. M. et al. The rapid evaluation of COVID-19 vaccination in emergency departments for underserved patients study. Ann. Emerg. Med. 78, 502–510 (2021).
Saluja, S. et al. Disparities in COVID-19 vaccine hesitancy among Los Angeles County adults after vaccine authorization. Prev. Med. Rep. 24, 101544 (2021).
Shallal, A. et al. Evaluation of COVID-19 vaccine attitudes among Arab American healthcare professionals living in the United States. Vaccines 9, 942 (2021).
Sirikalyanpaiboon, M. et al. COVID-19 vaccine acceptance, hesitancy, and determinants among physicians in a university-based teaching hospital in Thailand. BMC Infect. Dis. 21, 1174 (2021).
Solak, Ç., Peker-Dural, H., Karlıdağ, S. & Peker, M. Linking the behavioral immune system to COVID-19 vaccination intention: the mediating role of the need for cognitive closure and vaccine hesitancy. Pers. Individ. Dif. 185, 111245 (2022).
Spinewine, A. et al. Attitudes towards COVID-19 vaccination among hospital staff-understanding what matters to hesitant people. Vaccines 9, 469 (2021).
Stojanovic, J. et al. Global trends and correlates of COVID-19 vaccination hesitancy: findings from the iCARE study. Vaccines 9, 661 (2021).
Strathdee, S. A. et al. Correlates of coronavirus disease 2019 (COVID-19) vaccine hesitancy among people who inject drugs in the San Diego-Tijuana border region. Clin. Infect. Dis. https://doi.org/10.1093/cid/ciab975 (2021).
Szilagyi, P. G. et al. The role of trust in the likelihood of receiving a COVID-19 vaccine: results from a national survey. Prev. Med. 153, 106727 (2021).
Szilagyi, P. G. et al. Likelihood of COVID-19 vaccination by subgroups across the US: post-election trends and disparities. Hum. Vaccin. Immunother. 17, 3262–3267 (2021).
Tahir, A. I. et al. COVID-19 vaccine acceptance, hesitancy and refusal among Iraqi Kurdish population. Int. J. Health Sci. 16, 10–16 (2022).
Teasdale, C. A. et al. Parental plans to vaccinate children for COVID-19 in New York city. Vaccine 39, 5082–5086 (2021).
Thanapluetiwong, S., Chansirikarnjana, S., Sriwannopas, O., Assavapokee, T. & Ittasakul, P. Factors associated with COVID-19 vaccine hesitancy in Thai seniors. Patient Prefer. Adherence 15, 2389–2403 (2021).
Tsai, R. et al. COVID-19 vaccine hesitancy and acceptance among individuals with cancer, autoimmune diseases, or other serious comorbid conditions: cross-sectional, internet-based survey. JMIR Public Health Surveill. 8, e29872 (2022).
Uzochukwu, I. C. et al. COVID-19 vaccine hesitancy among staff and students in a Nigerian tertiary educational institution. Ther. Adv. Infect. Dis. 8, 20499361211054923 (2021).
Vieira Rezende, R. P. et al. Characteristics associated with COVID-19 vaccine hesitancy: a nationwide survey of 1000 patients with immune-mediated inflammatory diseases. Vaccine 39, 6454–6459 (2021).
Wang, S. X., Bell-Rogers, N., Dillard, D. & Harrington, M. A. COVID-19 vaccine hesitancy in Delaware’s underserved communities. Dela. J. Public Health 7, 168–175 (2021).
Wang, X., Lin, L., Xu, J., Wang, W. & Zhou, X. Expectant parents’ vaccine decisions influenced by the 2018 Chinese vaccine crisis: a cross-sectional study. Prev. Med. 145, 106423 (2021).
Waring, M. E. et al. Factors associated with mothers’ hesitancy to receive a COVID-19 vaccine. J. Behav. Med. https://doi.org/10.1007/s10865-021-00268-0 (2022).
Waters, A. R. et al. COVID-19 vaccine hesitancy among adolescent and young adult cancer survivors. JNCI Cancer Spectr. 5, pkab049 (2021).
West, H. et al. COVID-19 vaccine hesitancy among temporary foreign workers from Bangladesh. Health Syst. Reform 7, e1991550 (2021).
Willis, D. E. et al. COVID-19 vaccine hesitancy: race/ethnicity, trust, and fear. Clin. Transl. Sci. 14, 2200–2207 (2021).
Willis, D. E., Presley, J., Williams, M., Zaller, N. & McElfish, P. A. COVID-19 vaccine hesitancy among youth. Hum. Vaccin. Immunother. 17, 5013–5015 (2021).
Wiysonge, C. S. et al. COVID-19 vaccine acceptance and hesitancy among healthcare workers in South Africa. Expert Rev. Vaccines 21, 549–559 (2022).
Wu, H., Ward, M., Brown, A., Blackwell, E. & Umer, A. COVID-19 vaccine intent in Appalachian patients with multiple sclerosis. Mult. Scler. Relat. Disord. 57, 103450 (2021).
Wu, J. et al. COVID-19 vaccine hesitancy among Chinese population: a large-scale national study. Front. Immunol. 12, 781161 (2021).
Xu, Y. et al. A cross-sectional survey on covid-19 vaccine hesitancy among parents from Shandong vs. Zhejiang. Front. Public Health 9, 779720 (2021).
Zhang, M. X., Lin, X. Q., Chen, Y., Tung, T. H. & Zhu, J. S. Determinants of parental hesitancy to vaccinate their children against COVID-19 in China. Expert Rev. Vaccines 20, 1339–1349 (2021).
Zhang, P. et al. Who is more likely to hesitate to accept COVID-19 vaccine: a cross-sectional survey in China. Expert Rev. Vaccines 21, 397–406 (2022).
Zhao, Y. M. et al. Public willingness and determinants of COVID-19 vaccination at the initial stage of mass vaccination in China. Vaccines 9, 1172 (2021).
Opel, D. J. et al. Validity and reliability of a survey to identify vaccine-hesitant parents. Vaccine 29, 6598–6605 (2011).
Abd Halim, H., Abdul-Razak, S., Md Yasin, M. & Isa, M. R. Validation study of the Parent Attitudes About Childhood Vaccines (PACV) questionnaire: the Malay version. Hum. Vaccin. Immunother. 16, 1040–1049 (2020).
Al-Regaiey, K. A. et al. Influence of social media on parents’ attitudes towards vaccine administration. Hum. Vaccin. Immunother. 18, 1872340 (2021).
Alsuwaidi, A. R. et al. Vaccine hesitancy and its determinants among Arab parents: a cross-sectional survey in the United Arab Emirates. Hum. Vaccin. Immunother. 16, 3163–3169 (2020).
Bagateli, L. E. et al. COVID-19 vaccine hesitancy among parents of children and adolescents living in Brazil. Vaccines 9, 1115 (2021).
Beck, A., Bianchi, A. & Showalter, D. Evidence-based practice model to increase human papillomavirus vaccine uptake: a stepwise approach. Nurs. Womens Health 25, 430–436 (2021).
Bianco, A., Mascaro, V., Zucco, R. & Pavia, M. Parent perspectives on childhood vaccination: how to deal with vaccine hesitancy and refusal? Vaccine 37, 984–990 (2019).
Bonsu, N. E. M. et al. Understanding vaccine hesitancy among parents of children with autism spectrum disorder and parents of children with non-autism developmental delays. J. Child Neurol. 36, 911–918 (2021).
Bulun, M. A. & Acuner, D. Turkish adaptation and reliability and validity study of parent attitudes about childhood vaccines survey. J. Pediatr. Res. 7, 323–330 (2020).
Chang, J. & Kochel, R. Vaccine hesitancy and attributions for autism among racially and ethnically diverse groups of parents of children with autism spectrum disorder: a pilot study. Autism Res. 13, 1790–1796 (2020).
Chung-Delgado, K., Valdivia Venero, J. E. & Vu, T. M. Vaccine hesitancy: characteristics of the refusal of childhood vaccination in a Peruvian population. Cureus 13, e14105 (2021).
Clayton, K., Finley, C., Flynn, D. J., Graves, M. & Nyhan, B. Evaluating the effects of vaccine messaging on immunization intentions and behavior: evidence from two randomized controlled trials in Vermont. Vaccine 39, 5909–5917 (2021).
Cole, J., Berman, S., Gardner, J., McGuire, K. & Chen, A. M. H. Implementation of a motivational interviewing-based decision tool to improve childhood vaccination rates: pilot study protocol. Res. Social Adm. Pharm. 17, 619–624 (2020).
Cunningham, R. M., Guffey, D., Minard, C. G., Opel, D. J. & Boom, J. A. The effect of screening for vaccine hesitancy on the subsequent development of hesitancy: a randomized controlled trial, Houston, TX. Hum. Vaccin. Immunother. 17, 1994–2000 (2021).
Daley, M. F., Narwaney, K. J., Shoup, J. A., Wagner, N. M. & Glanz, J. M. Addressing parents’ vaccine concerns: a randomized trial of a social media intervention. Am. J. Prev. Med. 55, 44–54 (2018).
Eby, A. Z. Impacting parental vaccine decision-making. Pediatr. Nurs. 43, 22–29, 34 (2017).
Goin-Kochel, R. P. et al. Beliefs about causes of autism and vaccine hesitancy among parents of children with autism spectrum disorder. Vaccine 38, 6327–6333 (2020).
Henrikson, N. B. et al. Longitudinal trends in vaccine hesitancy in a cohort of mothers surveyed in Washington State, 2013–2015. Public Health Rep. 132, 451–454 (2017).
Henrikson, N. B. et al. Physician communication training and parental vaccine hesitancy: a randomized trial. Pediatrics 136, 70–79 (2015).
Hofstetter, A. M. et al. Parental vaccine hesitancy and declination of influenza vaccination among hospitalized children. Hosp. Pediatr. 8, 628–635 (2018).
Kalok, A. et al. Vaccine hesitancy towards childhood immunisation amongst urban pregnant mothers in Malaysia. Vaccine 38, 2183–2189 (2020).
Langkamp, D. L., Dusseau, A. & Brown, M. F. Vaccine hesitancy and low immunization rates in children with Down Syndrome. J. Pediatr. 223, 64–67 (2020).
Mical, R., Martin-Velez, J., Blackstone, T. & Derouin, A. Vaccine hesitancy in rural pediatric primary care. J. Pediatr. Health Care 35, 16–22 (2020).
Mohd Azizi, F. S., Kew, Y. & Moy, F. M. Vaccine hesitancy among parents in a multi-ethnic country, Malaysia. Vaccine 35, 2955–2961 (2017).
Napolitano, F., D’Alessandro, A. & Angelillo, I. F. Investigating Italian parents’ vaccine hesitancy: a cross-sectional survey. Hum. Vaccin. Immunother. 14, 1558–1565 (2018).
Olarewaju, V. O. et al. Application of the Parent Attitudes about Childhood Vaccines (PACV) survey in three national languages in Switzerland: exploratory factor analysis and Mokken scale analysis. Hum. Vaccin. Immunother. 17, 2652–2660 (2021).
Opel, D. J. et al. The architecture of provider-parent vaccine discussions at health supervision visits. Pediatrics 132, 1037–1046 (2013).
Opel, D. J. et al. The relationship between parent attitudes about childhood vaccines survey scores and future child immunization status: a validation study. JAMA Pediatr. 167, 1065–1071 (2013).
Opel, D. J. et al. Impact of childhood vaccine discussion format over time on immunization status. Acad. Pediatr. 18, 430–436 (2018).
Orr, C. & Beck, A. F. Measuring vaccine hesitancy in a minority community. Clin. Pediatr. 56, 784–788 (2017).
Reuben, R., Aitken, D., Freedman, J. L. & Einstein, G. Mistrust of the medical profession and higher disgust sensitivity predict parental vaccine hesitancy. PLoS ONE 15, e0237755 (2020).
Sabahelzain, M. M., van den Borne, B., Moukhyer, M. & Bosma, H. Determinants of measles vaccine hesitancy among Sudanese parents in Khartoum State, Sudan: a cross-sectional study. Vaccines 10, 6 (2022).
Sahni, L. C. et al. Vaccine hesitancy and illness perceptions: comparing parents of children with autism spectrum disorder to other parent groups. Child. Health Care 35, 385–402 (2020).
Sankaranarayanan, S., Jayaraman, A. & Gopichandran, V. Assessment of vaccine hesitancy among parents of children between 1 and 5 years of age at a tertiary care hospital in Chennai. Indian J. Community Med. 44, 394–396 (2019).
Strelitz, B. et al. Parental vaccine hesitancy and acceptance of seasonal influenza vaccine in the pediatric emergency department. Vaccine 33, 1802–1807 (2015).
Wagner, A. L. et al. Vaccine hesitancy and concerns about vaccine safety and effectiveness in Shanghai, China. Am. J. Prev. Med. 60, S77–S86 (2020).
Williams, J. T. B., Rice, J. D. & O’Leary, S. T. Associations between religion, religiosity, and parental vaccine hesitancy. Vaccine X 9, 100121 (2021).
Williams, S. E. et al. Screening tool predicts future underimmunization among a pediatric practice in Tennessee. Clin. Pediatr. 55, 537–542 (2016).
Williams, S. E. et al. A randomized trial to increase acceptance of childhood vaccines by vaccine-hesitant parents: a pilot study. Acad. Pediatr. 13, 475–480 (2013).
Yufika, A. et al. Parents’ hesitancy towards vaccination in Indonesia: a cross-sectional study in Indonesia. Vaccine 38, 2592–2599 (2020).
Akhmetzhanova, Z., Sazonov, V., Riethmacher, D. & Aljofan, M. Vaccine adherence: the rate of hesitancy toward childhood immunization in Kazakhstan. Expert Rev. Vaccines 19, 579–584 (2020).
Cunningham, R. M. et al. Development of a Spanish version of the parent attitudes about childhood vaccines survey. Hum. Vaccin. Immunother. 15, 1106–1110 (2019).
Cunningham, R. M. et al. Prevalence of vaccine hesitancy among expectant mothers in Houston, Texas. Acad. Pediatr. 18, 154–160 (2018).
Della Polla, G., Pelullo, C. P., Napolitano, F. & Angelillo, I. F. HPV vaccine hesitancy among parents in Italy: a cross-sectional study. Hum. Vaccin. Immunother. 16, 2744–2751 (2020).
Dubé, E. et al. Overview of knowledge, attitudes, beliefs, vaccine hesitancy and vaccine acceptance among mothers of infants in Quebec, Canada. Hum. Vaccin. Immunother. 15, 113–120 (2019).
Marshall, S., Moore, A. C., Sahm, L. J. & Fleming, A. Parent attitudes about childhood vaccines: point prevalence survey of vaccine hesitancy in an Irish population. Pharmacy 9, 188 (2021).
Moyer-Gusé, E., Robinson, M. J. & McKnight, J. The role of humor in messaging about the MMR vaccine. J. Health Commun. 23, 514–522 (2018).
Olarewaju, V. O. et al. The Youth Attitudes about Vaccines (YAV-5) scale: adapting the parent attitudes about childhood vaccines short scale for use with youth in German, French, and Italian in Switzerland, exploratory factor analysis and mokken scaling analysis. Hum. Vaccin. Immunother. 17, 5183–5190 (2021).
Roberts, J. R. et al. Vaccine hesitancy among parents of adolescents and its association with vaccine uptake. Vaccine 33, 1748–1755 (2015).
Ruggiero, K. M. et al. Parents’ intentions to vaccinate their children against COVID-19. J. Pediatr. Health Care 35, 509–517 (2021).
Voo, J. Y. H. et al. Vaccine knowledge, awareness and hesitancy: a cross sectional survey among parents residing at Sandakan District, Sabah. Vaccines 9, 1348 (2021).
Wallace, A. S. et al. Development of a valid and reliable scale to assess parents’ beliefs and attitudes about childhood vaccines and their association with vaccination uptake and delay in Ghana. Vaccine 37, 848–856 (2019).
Wang, Y. & Zhang, X. Influence of parental psychological flexibility on pediatric COVID-19 vaccine hesitancy: mediating role of self-efficacy and coping style. Front. Psychol. 12, 783401 (2021).
Whelan, S. O., Moriarty, F., Lawlor, L., Gorman, K. M. & Beamish, J. Vaccine hesitancy and reported non-vaccination in an Irish pediatric outpatient population. Eur. J. Pediatr. 180, 2839–2847 (2021).
Williams, J. T. B. & O’Leary, S. T. Denver religious leaders’ vaccine attitudes, practices, and congregational experiences. J. Relig. Health 58, 1356–1367 (2019).
Yörük, S. & Güler, D. Factors associated with pediatric vaccine hesitancy of parents: a cross-sectional study in Turkey. Hum. Vaccin. Immunother. 17, 4505–4511 (2021).
Zhang, H. et al. Vaccine hesitancy among parents and its influencing factors: a cross-sectional study in Guangzhou, China. Hum. Vaccin. Immunother. 17, 5153–5161 (2021).
Cataldi, J. R., Dempsey, A. F., Allison, M. A. & O’Leary, S. T. Impact of publicly available vaccination rates on parental school and child care choice. Vaccine 36, 4525–4531 (2018).
Cataldi, J. R., Dempsey, A. F. & O’Leary, S. T. Measles, the media, and MMR: impact of the 2014–15 measles outbreak. Vaccine 34, 6375–6380 (2016).
Cataldi, J. R. et al. Addressing personal parental values in decisions about childhood vaccination: measure development. Vaccine 37, 5688–5697 (2019).
McDonald, C. et al. a consent support resource with benefits and harms of vaccination does not increase hesitancy in parents–an acceptability study. Vaccines 8, 500 (2020).
Opel, D. J. et al. Previsit screening for parental vaccine hesitancy: a cluster randomized trial. Pediatrics 144, e20190802 (2019).
Williams, J. T. B. et al. Adapting and piloting a vaccine hesitancy questionnaire in rural Guatemala. Vaccine 39, 180–184 (2021).
Akbas Gunes, N. Parents’ perspectives about vaccine hesitancies and vaccine rejection, in the west of Turkey. J. Pediatr. Nurs. 53, e186–e194 (2020).
Aldakhil, H., Albedah, N., Alturaiki, N., Alajlan, R. & Abusalih, H. Vaccine hesitancy towards childhood immunizations as a predictor of mothers’ intention to vaccinate their children against COVID-19 in Saudi Arabia. J. Infect. Public Health 14, 1497–1504 (2021).
AlGoraini, Y. M. et al. Confidence toward vaccination as reported by parents of children admitted to a tertiary care hospital in Riyadh, Saudi Arabia: a cross sectional study. Vacunas 21, 95–104 (2020).
Alsubaie, S. S. et al. Vaccine hesitancy among Saudi parents and its determinants. Result from the WHO SAGE working group on vaccine hesitancy survey tool. Saudi Med. J. 40, 1242–1250 (2019).
Connors, J. T., Hodges, E. A., DʼAuria, J. & Windham, L. Implementing vaccine hesitancy screening for targeted education. J. Am. Assoc. Nurse Pract. 30, 450–459 (2018).
Dasgupta, P., Bhattacherjee, S., Mukherjee, A. & Dasgupta, S. Vaccine hesitancy for childhood vaccinations in slum areas of Siliguri, India. Indian J. Public Health 62, 253–258 (2018).
Johnson, K. D. et al. Combatting a “twin-demic”: a quantitative assessment of COVID-19 and influenza vaccine hesitancy in primary care patients. Health Promot. Perspect. 11, 179–185 (2021).
Krishnamoorthy, Y. et al. Factors related to vaccine hesitancy during the implementation of Measles-Rubella campaign 2017 in rural Puducherry–a mixed-method study. J. Fam. Med. Prim. Care 8, 3962–3970 (2019).
Masters, N. B., Tefera, Y. A., Wagner, A. L. & Boulton, M. L. Vaccine hesitancy among caregivers and association with childhood vaccination timeliness in Addis Ababa, Ethiopia. Hum. Vaccin. Immunother. 14, 2340–2347 (2018).
Miko, D., Costache, C., Colosi, H. A., Neculicioiu, V. & Colosi, I. A. Qualitative assessment of vaccine hesitancy in Romania. Medicina 55, 282 (2019).
Sharma, S., Akhtar, F., Singh, R. K. & Mehra, S. Understanding the three As (awareness, access, and acceptability) dimensions of vaccine hesitancy in Odisha, India. Clin. Epidemiol. Glob. Health 8, 399–403 (2020).
Soysal, G., Durukan, E. & Akdur, R. The evaluation of vaccine hesitancy and refusal for childhood vaccines and the covid-19 vaccine in individuals aged between 18 and 25 years. Turkish J. Immunol. 9, 120–127 (2021).
Khezong, A. et al. Association between adult vaccine hesitancy and parental acceptance of childhood COVID-19 vaccines: a web-based survey in a northwestern region in China. Vaccines 9, 1088 (2021).
Akel, K. B., Masters, N. B., Shih, S. F., Lu, Y. & Wagner, A. L. Modification of a vaccine hesitancy scale for use in adult vaccinations in the United States and China. Hum. Vaccin. Immunother. 17, 2639–2646 (2021).
Chen, M. et al. An online survey of the attitude and willingness of Chinese adults to receive COVID-19 vaccination. Hum. Vaccin. Immunother. 17, 2279–2288 (2021).
Dolu, İ., Turhan, Z. & Yalnız Dilcen, H. COVID-19 vaccine acceptance is associated with vaccine hesitancy, perceived risk and previous vaccination experiences. Disaster Med. Public Health Prep. https://doi.org/10.1017/dmp.2021.370 (2021).
Domek, G. J. et al. Measuring vaccine hesitancy: field testing the WHO SAGE Working Group on Vaccine Hesitancy survey tool in Guatemala. Vaccine 36, 5273–5281 (2018).
Gatwood, J. et al. Extent of and reasons for vaccine hesitancy in adults at high-risk for pneumococcal disease. Am. J. Health Promot. 35, 908–916 (2021).
Han, Y. et al. Parental category B vaccine hesitancy and associated factors in China: an online cross-sectional survey. Expert Rev. Vaccines 21, 145–153 (2021).
He, K., Mack, W. J., Neely, M., Lewis, L. & Anand, V. Parental perspectives on immunizations: impact of the COVID-19 pandemic on childhood vaccine hesitancy. J. Community Health 47, 39–52 (2022).
Helmkamp, L. J. et al. A validated modification of the vaccine hesitancy scale for childhood, influenza and HPV vaccines. Vaccine 39, 1831–1839 (2021).
Jones, D. L. et al. Severe acute respiratory syndrome coronavirus 2: vaccine hesitancy among underrepresented racial and ethnic groups with HIV in Miami, Florida. Open Forum Infect. Dis. 8, ofab154 (2021).
Kasrine Al Halabi, C. et al. Attitudes of Lebanese adults regarding COVID-19 vaccination. BMC Public Health 21, 998 (2021).
Kempe, A. et al. Parental hesitancy about routine childhood and influenza vaccinations: a national survey. Pediatrics 146, e20193852 (2020).
Kim, H. W. et al. Perceptions of nurses on human papillomavirus vaccinations in the Republic of Korea. PLoS ONE 14, e0211475 (2019).
Liu, P. L., Zhao, X. & Wan, B. COVID-19 information exposure and vaccine hesitancy: the influence of trust in government and vaccine confidence. Psychol. Health Med. https://doi.org/10.1080/13548506.2021.2014910 (2021).
Lu, F. & Sun, Y. COVID-19 vaccine hesitancy: the effects of combining direct and indirect online opinion cues on psychological reactance to health campaigns. Comput. Hum. Behav. 127, 107057 (2022).
Lu, J. et al. Sensitivity to COVID-19 vaccine effectiveness and safety in Shanghai, China. Vaccines 9, 472 (2021).
Lu, X. et al. Low willingness to vaccinate against herpes zoster in a Chinese metropolis. Hum. Vaccin. Immunother. 17, 4163–4170 (2021).
Lu, X. et al. Gap between willingness and behavior in the vaccination against influenza, pneumonia, and herpes zoster among Chinese aged 50–69 years. Expert Rev. Vaccines 20, 1147–1152 (2021).
Luyten, J., Bruyneel, L. & van Hoek, A. J. Assessing vaccine hesitancy in the UK population using a generalized vaccine hesitancy survey instrument. Vaccine 37, 2494–2501 (2019).
Önal, Ö., Eroğlu, H. N., Evcil, F. Y., Kişioğlu, A. N. & Uskun, E. Validity and reliability of Turkish version of the Vaccine Hesitancy Scale. Turk. Arch. Pediatr. 56, 230–235 (2021).
Ren, J. et al. The demographics of vaccine hesitancy in Shanghai, China. PLoS ONE 13, e0209117 (2018).
Sabahelzain, M. M. et al. Psychometric properties of the adapted measles vaccine hesitancy scale in Sudan. PLoS ONE 15, e0237171 (2020).
Sadaqat, W. et al. Determination of COVID-19 vaccine hesitancy among university students. Cureus 13, e17283 (2021).
Shapiro, G. K. et al. The vaccine hesitancy scale: psychometric properties and validation. Vaccine 36, 660–667 (2018).
Shen, X. et al. Assessing the COVID-19 vaccine hesitancy in the Chinese adults using a generalized vaccine hesitancy survey instrument. Hum. Vaccin. Immunother. 17, 4005–4012 (2021).
Shih, S. F. et al. Vaccine hesitancy and rejection of a vaccine for the novel coronavirus in the United States. Front. Immunol. 12, 558270 (2021).
Szilagyi, P. G. et al. Prevalence and characteristics of HPV vaccine hesitancy among parents of adolescents across the US. Vaccine 38, 6027–6037 (2020).
Temsah, M. H. et al. Parental attitudes and hesitancy about COVID-19 vs. routine childhood vaccinations: a national survey. Front. Public Health 9, 752323 (2021).
Thaker, J. The persistence of vaccine hesitancy: COVID-19 vaccination intention in New Zealand. J. Health Commun. 26, 104–111 (2021).
Turhan, Z., Dilcen, H. Y. & Dolu, İ. The mediating role of health literacy on the relationship between health care system distrust and vaccine hesitancy during COVID-19 pandemic. Curr. Psychol. https://doi.org/10.1007/s12144-021-02105-8 (2021).
Vallis, M. & Glazer, S. Protecting individuals living with overweight and obesity: attitudes and concerns toward COVID-19 vaccination in Canada. Obesity 29, 1128–1137 (2021).
Wagner, A. L. et al. Comparisons of vaccine hesitancy across five low- and middle-income countries. Vaccines 7, 155 (2019).
Wagner, A. L., Shotwell, A. R., Boulton, M. L., Carlson, B. F. & Mathew, J. L. Demographics of vaccine hesitancy in Chandigarh, India. Front. Med. 7, 585579 (2020).
Wang, Q. et al. Delays in routine childhood vaccinations and their relationship with parental vaccine hesitancy: a cross-sectional study in Wuxi, China. Expert Rev. Vaccines 21, 135–143 (2021).
Wang, Q. et al. Vaccine hHesitancy: COVID-19 and influenza vaccine willingness among parents in Wuxi, China–a cross-sectional study. Vaccines 9, 342 (2021).
Xu, Y. et al. COVID-19 vaccination attitudes with neuromyelitis optica spectrum disorders: vaccine hesitancy and coping style. Front. Neurol. 12, 717111 (2021).
Yeşiltepe, A., Aslan, S. & Bulbuloglu, S. Investigation of perceived fear of COVID-19 and vaccine hesitancy in nursing students. Hum. Vaccin. Immunother. 17, 5030–5037 (2021).
Duong, T. V. et al. Oxford COVID-19 vaccine hesitancy in school principals: impacts of gender, well-being, and coronavirus-related health literacy. Vaccines 9, 958 (2021).
Guaracha-Basáñez, G. et al. COVID-19 vaccine hesitancy among Mexican outpatients with rheumatic diseases. Hum. Vaccin. Immunother. 17, 5038–5047 (2021).
Joshi, A. et al. COVID-19 vaccine hesitancy in healthcare workers amidst the second wave of the pandemic in India: a single centre study. Cureus 13, e17370 (2021).
Zhang, X., Guo, Y., Zhou, Q., Tan, Z. & Cao, J. The mediating roles of medical mistrust, knowledge, confidence and complacency of vaccines in the pathways from conspiracy beliefs to vaccine hesitancy. Vaccines 9, 1342 (2021).
Pomares, T. D. et al. Association of cognitive biases with human papillomavirus vaccine hesitancy: a cross-sectional study. Hum. Vaccin. Immunother. 16, 1018–1023 (2020).
Ashkenazi, S. et al. The relationship between parental source of information and knowledge about measles / measles vaccine and vaccine hesitancy. Vaccine 38, 7292–7298 (2020).
Biswas, N., Mustapha, T., Khubchandani, J. & Price, J. H. The nature and extent of COVID-19 vaccination hesitancy in healthcare workers. J. Community Health 46, 1244–1251 (2021).
Boattini, M. et al. Rubella serosurvey and factors related to vaccine hesitancy in childbearing women in Italy. Prev. Med. Rep. 15, 100945 (2019).
Browne, S. K. et al. Coronavirus disease 2019 (COVID-19) vaccine hesitancy among physicians, physician assistants, nurse practitioners, and nurses in two academic hospitals in Philadelphia. Infect. Control Hosp. Epidemiol. https://doi.org/10.1017/ice.2021.410 (2021).
Dybsand, L. L., Hall, K. J. & Carson, P. J. Immunization attitudes, opinions, and knowledge of healthcare professional students at two Midwestern universities in the United States. BMC Med. Educ. 19, 242 (2019).
Gao, X., Li, H., He, W. & Zeng, W. COVID-19 vaccine hesitancy among medical students: the next COVID-19 challenge in Wuhan, China. Disaster Med. Public Health Prep. https://doi.org/10.1017/dmp.2021.291 (2021).
Gerber, J. E. et al. Vaccinomics: a cross-sectional survey of public values. Hum. Vaccin. Immunother. 17, 2999–3015 (2021).
Giambi, C. et al. Parental vaccine hesitancy in Italy – results from a national survey. Vaccine 36, 779–787 (2018).
Guay, M., Gosselin, V., Petit, G., Baron, G. & Gagneur, A. Determinants of vaccine hesitancy in Quebec: a large population-based survey. Hum. Vaccin. Immunother. 15, 2527–2533 (2019).
Harapan, H. et al. Vaccine hesitancy among communities in ten countries in Asia, Africa, and South America during the COVID-19 pandemic. Pathog. Glob. Health 116, 236–243 (2022).
Hornsey, M. J., Lobera, J. & Díaz-Catalán, C. Vaccine hesitancy is strongly associated with distrust of conventional medicine, and only weakly associated with trust in alternative medicine. Soc. Sci. Med. 255, 113019 (2020).
Hu, Y., Chen, Y., Liang, H. & Wang, Y. Reliability and validity of a survey to identify vaccine hesitancy among parents in Changxing county, Zhejiang province. Hum. Vaccin. Immunother. 15, 1092–1099 (2019).
Johnson, D. K. et al. Combating vaccine hesitancy with vaccine-preventable disease familiarization: an interview and curriculum intervention for college students. Vaccines 7, 39 (2019).
Kassianos, G. et al. Motors of influenza vaccination uptake and vaccination advocacy in healthcare workers: a comparative study in six European countries. Vaccine 36, 6546–6552 (2018).
Klassen, A. C. et al. Formative research to address vaccine hesitancy in Tajikistan. Vaccine 39, 1516–1527 (2021).
Liu, Y. et al. COVID-19 vaccination in people living with HIV (PLWH) in China: a cross sectional study of vaccine hesitancy, safety, and immunogenicity. Vaccines 9, 1458 (2021).
Paoli, S. et al. Assessing vaccine hesitancy among healthcare workers: a cross-sectional study at an Italian paediatric hospital and the development of a healthcare worker’s vaccination compliance index. Vaccines 7, 201 (2019).
Rahman, M., Hossain, A., Sufian, A. & Anwar, N. COVID-19 vaccine demand, hesitancy, and nationalism: a case of protection motivation behavior in Bangladesh. J. Infect. Dev. Ctries 15, 1388–1395 (2021).
Raude, J. et al. Opening the ‘Vaccine Hesitancy’ black box: how trust in institutions affects French GPs’ vaccination practices. Expert Rev. Vaccines 15, 937–948 (2016).
Schwarzinger, M., Watson, V., Arwidson, P., Alla, F. & Luchini, S. COVID-19 vaccine hesitancy in a representative working-age population in France: a survey experiment based on vaccine characteristics. Lancet Public Health 6, e210–e221 (2021).
Stoeckel, F., Carter, C., Lyons, B. A. & Reifler, J. Association of vaccine hesitancy and immunization coverage rates in the European Union. Vaccine 39, 3935–3939 (2021).
Tomljenovic, M., Petrovic, G., Antoljak, N. & Hansen, L. Vaccination attitudes, beliefs and behaviours among primary health care workers in northern Croatia. Vaccine 39, 738–745 (2021).
Verger, P. et al. Vaccine hesitancy among hospital staff physicians: a cross-sectional survey in France in 2019. Vaccine 39, 4481–4488 (2021).
Verger, P. et al. Vaccine hesitancy among general practitioners and its determinants during controversies: a national cross-sectional survey in France. EBioMedicine 2, 891–897 (2015).
Carranza, D., Dub, T. & Sivelä, J. Vaccine Hesitancy and Uptake. From Research and Practices to Implementation (Finnish Institute for Health and Welfare (THL), 2021); https://eu-jav.com/public_deliverable/deliverable-8-1-vaccine-hesitancy-and-uptake-from-research-and-practices-to-implementation/
Merriam-Webster Dictionary Hesitancy https://www.merriam-webster.com/dictionary/hesitancy (2021).
Merriam-Webster Dictionary Vaccine Hesitancy https://www.merriam-webster.com/dictionary/vaccine%20hesitancy (2021).
Siani, A. et al. Investigating the determinants of vaccine hesitancy within undergraduate students’ social sphere. Z. Gesundh. Wiss. https://doi.org/10.1007/s10389-021-01538-6 (2021).
Strong, H., Reiter-Purtill, J., Howarth, T., West-Smith, L. & Zeller, M. H. Early COVID-19 vaccine hesitancy characteristics in mothers following bariatric surgery. Obes. Surg. 32, 852–860 (2022).
Lavail, K. H. & Kennedy, A. M. The role of attitudes about vaccine safety, efficacy, and value in explaining parents’ reported vaccination behavior. Health Educ. Behav. 40, 544–551 (2013).
Frew, P. M. et al. Development of a measure to assess vaccine confidence among men who have sex with men. Expert Rev. Vaccines 17, 1053–1061 (2018).
World Bank Country and Lending Groups (The World Bank, 2021); https://datahelpdesk.worldbank.org/knowledgebase/articles/906519-world-bank-country-and-lending-groups
Hong, Q. N. et al. Mixed Methods Appraisal Tool (MMAT), version 2018 (Canadian Intellectual Property Office, Industry Canada, 2018).
Hong, Q. N. et al. Reporting the Results of the MMAT (Version 2018) http://mixedmethodsappraisaltoolpublic.pbworks.com/w/file/fetch/140056890/Reporting%20the%20results%20of%20the%20MMAT.pdf (2020).
Acknowledgements
J.L.A.H. and M.E.J.L.H. received funding from The Netherlands Organisation for Health Research and Development (ZonMw project number 839190002). The funders had no role in study design, data collection and analysis, decision to publish or preparation of the manuscript. We thank J. van Haren for her valuable contribution in sorting and organizing the data of this systematic review.
Author information
Authors and Affiliations
Contributions
D.B.-V., J.L.A.H., O.V. and M.E.J.L.H. designed the project and analysed the data. D.B.-V., J.L.A.H., L.V., O.V. and M.E.J.L.H. interpreted the data. The manuscript, figures and tables were drafted by D.B.-V. and edited by J.L.A.H., L.V., O.V. and M.E.J.L.H.
Corresponding author
Ethics declarations
Competing interests
The authors declare no competing interests.
Peer review
Peer review information
Nature Human Behaviour thanks Chuanxi Fu, Amalie Dyda and the other, anonymous, reviewer(s) for their contribution to the peer review of this work. Peer reviewer reports are available.
Additional information
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Supplementary information
Supplementary Information
Supplementary methods, PRISMA 2020 for abstracts checklist, PRISMA 2020 checklist.
Supplementary Table 1
Overview and characteristics of included studies.
Supplementary Table 2
Overview of extracted excerpts.
Supplementary Table 3
Overview of vaccine hesitancy subpopulations.
Supplementary Table 4
Overview of studies describing a measurement of vaccine hesitancy.
Rights and permissions
Springer Nature or its licensor holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
About this article
Cite this article
Bussink-Voorend, D., Hautvast, J.L.A., Vandeberg, L. et al. A systematic literature review to clarify the concept of vaccine hesitancy. Nat Hum Behav 6, 1634–1648 (2022). https://doi.org/10.1038/s41562-022-01431-6
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1038/s41562-022-01431-6
This article is cited by
-
Identifying vaccine-hesitant subgroups in the Western Pacific using latent class analysis
npj Vaccines (2025)
-
Development and validation of an Arabic tool for assessment of post-vaccination confidence in COVID-19 vaccines (ARAB-VAX-CONF)
Journal of the Egyptian Public Health Association (2024)
-
Factors associated with SARS-CoV-2 vaccine hesitancy after stroke: a cross-sectional study
BMC Public Health (2024)
-
Facilitators and challenges in collaboration between public health units and faith-based organizations to promote COVID-19 vaccine confidence in Ontario
International Journal for Equity in Health (2024)
-
An effective COVID-19 vaccine hesitancy intervention focused on the relative risks of vaccination and infection
Scientific Reports (2024)