Resistance to vaccination has been present in the United States since the 1850s when smallpox mandates were seen as a violation of liberty. In 1879, in response to states’ attempts to enforce vaccination when smallpox again became epidemic, the Anti-Vaccination Society of America was formed. Similarly, in the United Kingdom, an antivaccination movement grew against compulsory vaccination, which spread throughout Europe.1 The second half of the 1900s saw the introduction of a number of vaccines able to prevent childhood death, including immunizations against polio, measles, tetanus, pertussis, and tuberculosis. Parents overwhelmingly accepted vaccinations for their children, leading to significant decreases in infectious disease outbreaks and childhood morbidity and mortality. However, a resurgence of antivaccine movements occurred in the 1970s in the United Kingdom when the safety of the whole cell pertussis vaccine was questioned. In 1982, the documentary “DTP: Vaccination Roulette” ignited controversy in the United States.2 Andrew Wakefield’s erroneous publication in 1998 linking autism and the Measles, Mumps, and Rubella vaccine created a worldwide crisis; the presence of the Internet now allows massive diffusion of information by antivaccination activists.3 Today, antivaccination movements can be found worldwide.4
Internationally, rates of vaccine-preventable diseases (VPDs) have increased in many communities in both developed and developing countries due to low or decreasing vaccination rates.5,6 Recent studies estimate that approximately 1 in 8 children younger than age 2 years in the United States are undervaccinated due to parental choice and a majority of pediatricians report at least one vaccine refusal per month.7,8 The most recent National Immunization Survey shows 11 states in which ≥4% of children entering kindergarten have an exemption from school-entry vaccine mandates.9 This translates to increased periods of risk exposure for children and outbreaks of VPDs. In 2014, 644 cases of measles were recorded, with 23 outbreaks affecting 27 states.10 Recent pertussis outbreaks have been linked to undervaccination;11 in a California outbreak, unvaccinated children were 8 times more likely to develop pertussis than vaccinated children.12 In light of the alarming public health implications of vaccine hesitancy, it is imperative that both health care providers and policymakers confront this issue to maintain effective immunization programs.
Defining Vaccine Hesitancy
Individuals who are vaccine hesitant are a heterogeneous group who hold varying degrees of indecision about specific vaccines or vaccination in general.4 Along this spectrum of indecision, there is a range of vaccine uptake, depending on additional influences that move an individual toward or away from ultimately accepting a particular vaccine. Building on expertise from multiple fields, including behavioral theory, social psychology, bioethics, and behavioral economics, there are a growing number of models to describe the heterogeneity of vaccine hesitancy.4,8,13–15 These models integrate the relevant social, cultural, political, and personal factors that impact vaccine decision-making.
Keane et al.,13 in a survey-based study, identified four groups of parents who were (1) convinced of the benefit of vaccination, (2) emotionally invested in their children and cautious about vaccination, (3) more skeptical of vaccines, and (4) distrustful of vaccines and vaccination policies. In another study conducted in multiple lower-income countries, parents who do not accept vaccines were categorized as those who (1) are willing to go to immunization centers, but are logistically unable to do so; (2) refuse to go based on inadequate services, and (3) question the need for vaccination.15 A systematic review by Leask et al.14 identified a spectrum of parent attitudes on vaccination, and consequently developed five groups based on their results and expert opinion that can help classify parents along this spectrum. These include (1) unquestioning acceptors, (2) cautious acceptors, (3) parents who are hesitant, (4) late or selective acceptors, and (5) those who refuse all vaccines.14
Although there are a small number of parents who unequivocally refuse all vaccines, and many parents who overwhelmingly accept vaccines, many families fall between these extremes and express some level of vaccine hesitancy, as characterized by these different models.8 This group of individuals hesitant to vaccinate has been a focus for more recent and ongoing research to identify strategies that can effectively move individuals toward vaccine acceptance.16
Factors Contributing to Vaccine Hesitancy
Causes of vaccine hesitancy are best understood when placed in the appropriate historical, political, and socio-cultural contexts. Parents’ decisions to vaccinate are influenced by multiple factors, as outlined by Dube et al.17 These include parent-specific characteristics such as previous experience with VPDs or relationship with the health care system, community-level factors such as social norms, and external factors such as vaccine policy. All of these factors must be considered together to better understand how to combat hesitancy within our practices and within our communities.8
Knowledge and Information Sources
Access to vaccine information and misinformation from a wide range of sources has influenced vaccine decision-making. Parents now hear a multitude of messages, often conflicting, and this can lead to questions about vaccines. Not all of this information is accurate and instead contributes to misperceptions that can influence vaccine acceptance. As summarized by Dube et al.,17 media coverage (in print and on television) with negative stories about vaccine safety correlate with increased incidence of VPDs. It is also known that parents who lack sufficient knowledge about vaccines or VPDs are more likely to have negative attitudes toward immunizations, providers, immunization requirements, and trust in the individuals and institutions responsible for immunization policy.18 Providing accurate information to boost knowledge about vaccines and VPDs will therefore be one of many important strategies to reduce hesitancy; however, the way in which information is provided is equally as important. Individuals often seek information that already aligns with their beliefs—as such accessing different media sources may reinforce rather than alter hesitancy.
Experiences with Vaccination and Vaccine-Preventable Diseases
Parents’ perception of the value of vaccines is based on their perceived risk of VPDs. Many parents have little experience with VPDs, and therefore may have more fear of vaccines than the diseases they are designed to eliminate. As long as vaccines continue to be successful, the risk of obtaining a VPD may not motivate parents to immunize their children. Instead, parents may be more focused on vaccine safety and raise concerns about potential short-term and long-term side effects or the number and timing of injections.19
The Role of Health Professionals and Their Recommendations
Health professionals are essential promoters of vaccine acceptance. Despite the availability of information from a wide range of resources, providers remain the most important predictor of vaccine acceptance. Recent studies have emphasized the importance of a strong recommendation.20–22 However, increasingly, parents may question information received from providers. Therefore, providers must be prepared to communicate with parents and patients about specific concerns that are raised by a family.23 The rapidly evolving immunization schedule can make it difficult to have all of the answers when questions do arise, which may also challenge the parent-provider relationship. Finally, providers themselves may have questions and concerns about vaccines, especially new vaccines. If providers themselves are hesitant, they are less likely to encourage their patients to vaccinate.24
The Role of the Public Health System
There are three primary ways the public health system may influence vaccine acceptance: (1) the development and implementation of immunization recommendations; (2) vaccine policy such as school-entry mandates; and (3) vaccine safety monitoring. In the US, all immunization recommendations are developed by the Advisory Commission on Immunization Practices (ACIP), a part of the Centers for Disease Control and Prevention. ACIP recommendations send an important message to both providers and parents. Providers may be more likely to give a strong recommendation to parents for vaccines that are recommended for routine administration by the ACIP, and parents may be more inclined to view recommended vaccines as important to their child. Also, recommendations influence state policies about vaccination and school-entry requirements.
The public health system also serves to educate the community about vaccines and VPDs, and ensure them that vaccines are safe. Vaccine safety is one of the leading concerns among parents, and there is an extensive vaccine safety monitoring infrastructure hosted by multiple agencies within the public health system. Ongoing surveillance, and programs such as the Vaccine Injury Compensation Program, which provides financial compensation to families who may have experienced a vaccine-associated adverse event, may influence confidence in the immunization program. Conversely, any miscommunication from public health agencies can reduce confidence in vaccine safety and increase hesitancy. As an example, in 2001 the US Food and Drug Administration removed thimerosal from the majority of vaccines due to a theoretical risk of mercury toxicity, even though this outcome was not supported by evidence. This decision inadvertently raised concern that thimerosal is not a safe vaccine additive and many individuals refuse vaccines containing thimerosal as a preservative.25
Social Norms and Parental Responsibility
Parents’ motivation to vaccinate their children is also influenced by social norms, which are the rules that a group uses for appropriate and inappropriate values, beliefs, attitudes, and behaviors.26 Physicians, other parents, family members, and collective-community values can inform decision-making in both directions. In many communities, vaccinating a child is viewed as a positive parental decision and a social responsibility; in communities where many parents are hesitant about vaccines, and vocalize this hesitancy, the reverse may be true.8
Underlying many of the factors described above is trust. With rapid-fire information dissemination, it is easy for parents to hear inconsistent messages about vaccines that erode trust in vaccines, providers, and the health care system. The issue of trust has been described as the vaccine-confidence gap.27 Several factors determine whether the public trusts an individual or institution. The trustworthiness of the information source, which may be the pharmaceutical industry, the government, a health care provider, or even a community member, impacts the credibility of the information. For example, some individuals view pharmaceutical companies with a skeptical eye and consider vaccines as a product designed to ensure profit at the expense of safety or true need. Additionally, many have embraced “natural” products and alternative medicine—distrusting many medical interventions including vaccines, which may be considered an ‘unnatural’ way to boost the immune system.23
In the US, 48 of 50 states accept religious exemptions from school-entry mandates. Although there are few canonical bases for refusing vaccination, passages in religious texts are left open to interpretation for each believer within each tradition. Some faith groups eschew all medical intervention, whereas others have specific beliefs related to vaccine components. It can be difficult to move strongly held religious beliefs, although providers can impart information about certain facts, such as cell-line origins or porcine content, which may allay some concerns.28
Addressing Vaccine Hesitancy
There are a growing number of suggested approaches to move parents toward vaccine acceptance. Many of these approaches are well described in a recent review by Gowda and Dempsey.8 Tailored messaging based on where one fits on the vaccine-hesitance spectrum is one strategy. For example, if a parent has refused vaccines in the past, the conversation should begin with asking permission to discuss vaccines, followed by allowing exploration of the parent’s specific concerns, and eliciting what would motivate a change in position.14 Educational materials should be tailored to the experiences of the patient or parent to increase their salience. As many antivaccine messages are delivered by influential figures, “celebrity immunization champions” should also be identified who are likeable, trustworthy, and have common goals with the audience. Shelby and Ernst29 also describe storytelling as a method of disseminating messages, as parents and patients may be more motivated by stories than scientific communication. This strategy has been effectively used by the antivaccine movement.
Providers themselves must also be confident in vaccine safety and efficacy and translate this confidence into a strong recommendation, as a physician’s recommendation is frequently cited as the reason parents choose to vaccinate their children.30 Parents’ concerns should be elicited through questioning so that they can be specifically addressed. Providers must prioritize communicating the need for vaccination and be able to address concerns about vaccine safety with comprehensive information. This means having resources readily available so that providers can remain up-to-date and have their own concerns answered. Resources can also be shared with parents when there is not enough time for an in-depth discussion. Lastly, providers can also lead by example, complying with any immunization recommendations for themselves.24
The majority of methods explored for moving families who are hesitant about vaccines toward acceptance focus on the provider-patient relationship. Public health policy can also be used to increase immunization rates. School-entry mandates provide an excellent example of a policy that has contributed to significant increases in vaccination rates. Unfortunately, states with more lenient policies have higher exemption rates. However, almost every state has a wide range of policies that allows parents to obtain personal belief and/or religious exemptions for mandates. Studies show that states with more lenient policies have higher exemption rates and states with higher rates are more likely to experience outbreaks of VPDs.19,31,32 This suggests that tightening exemption policies can make it more difficult for parents hesitant to vaccinate to delay or refuse vaccination. In fact, there is legal precedence for compulsory vaccination when the benefit of the public outweighs a person’s liberty.33 Although some may argue that this takes away individual choice, vaccines are public health tools that benefit the entire community. Future exploration of stricter exemption laws, economic incentives for those who are vaccinated, restrictions on social activities, and stricter mandates may be necessary to protect public safety.34
Additionally, policies at the provider level may also be pursued. Family dismissal in the setting of vaccine refusal is challenging and there are ethical arguments that support both dismissal and maintenance of the provider-family relationship. Providers must balance a desire to maintain their relationship with the family and their desire to provide what they consider standard of care and protect other families in their practice. Practices have developed a range of policies to guide their response in the setting of vaccine refusal that may include provision of vaccine education, signing a declination form or, when these efforts are not successful, dismissal. The American Academy of Pediatrics provides guidance to support the development of practice policies. Ultimately, implementing a consistent policy may send a strong message to parents that vaccines are a key component of the child-health platform.
Ongoing research is needed to develop the most effective strategies to confront vaccine acceptance. Such strategies will require a multifaceted approach. A systematic review of interventions designed to reduce parental hesitancy identified three key areas: state laws, school- and state-level implementation of laws, and parent-centered education. However, there is limited evidence to guide widespread implementation of a specific strategy at this time to effectively minimize the impact of vaccine refusal.35 Public health strategies that have been tested to counter antivaccination movements have focused mainly on reducing the knowledge gaps and these have not been successful. Indeed, multiple studies have shown that increasing knowledge alone will not change behaviors.3
As outlined in a recent report by the American Academy of Arts and Sciences, it will be more important to focus efforts on determining how parents make decisions about immunization, how their attitudes and beliefs develop, and where they obtain information.36 A focus on the health care visit can help elucidate the most effective communication strategies for both presenting information and negotiating with parents who are hesitant. Finally, a focus on communities most at-risk for high rates of hesitancy can identify socio-cultural factors that influence vaccine decision-making to inform the development of effective community-based interventions. Vaccine hesitancy presents a significant challenge that will require a multidisciplinary approach. The profound impact of immunizations on public health mandates continued attention to this topic to prevent the reemergence of diseases preventable by vaccination.
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- Poland GA, Jacobson RM. The age-old struggle against the antivaccinationists. N Engl J Med. 2011;364:97–99. doi:10.1056/NEJMp1010594 [CrossRef]
- Dube E, Vivion M, MacDonald NE. Vaccine hesitancy, vaccine refusal and the anti-vaccine movement: influence, impact and implications. Expert Rev Vaccines. 2015;14:99–117. doi:10.1586/14760584.2015.964212 [CrossRef]
- Larson HJ, Jarrett C, Eckersberger E, Smith DM, Paterson P. Understanding vaccine hesitancy around vaccines and vaccination from a global perspective: a systematic review of published literature, 2007–2012. Vaccine. 2014;32:2150–2159. doi:10.1016/j.vaccine.2014.01.081 [CrossRef]
- Laxminarayan R, Ganguly NK. India’s vaccine deficit: why more than half of Indian children are not fully immunized, and what can--and should--be done. Health Aff (Millwood). 2011;30:1096–1103. doi:10.1377/hlthaff.2011.0405 [CrossRef]
- Sugerman DE, Barskey AE, Delea MG, et al. Measles outbreak in a highly vaccinated population, San Diego, 2008: role of the intentionally undervaccinated. Pediatrics. 2010;125:747–755. doi:10.1542/peds.2009-1653 [CrossRef]
- Glanz JM, Newcomer SR, Narwaney KJ, et al. A population-based cohort study of undervaccination in 8 managed care organizations across the United States. JAMA Pediatr. 2013;167:274–281. doi:10.1001/jamapediatrics.2013.502 [CrossRef]
- Gowda C, Dempsey AF. The rise (and fall?) of parental vaccine hesitancy. Human Vaccin Immunother. 2013;9:1755–1762. doi:10.4161/hv.25085 [CrossRef]
- Seither R, Masalovich S, Knighton CL, et al. Vaccination coverage among children in kindergarten - United States, 2013–14 school year. MMWR Morb Mortal Wkly Rep. 2014;63:913–920.
- Centers for Disease Control and Prevention. Measles cases and outbreaks. www.cdc.gov/measles/cases-outbreaks.html#outbreaks. Accessed April 1, 2015.
- Glanz JM, Narwaney KJ, Newcomer SR, et al. Association between undervaccination with diphtheria, tetanus toxoids, and acellular pertussis (DTaP) vaccine and risk of pertussis infection in children 3 to 36 months of age. JAMA Pediatr. 2013;167:1060–1064. doi:10.1001/jamapediatrics.2013.2353 [CrossRef]
- Glanz JM, McClure DL, Magid DJ, et al. Parental refusal of pertussis vaccination is associated with an increased risk of pertussis infection in children. Pediatrics. 2009;123:1446–1451. doi:10.1542/peds.2008-2150 [CrossRef]
- Keane MT, Walter MV, Patel BI, et al. Confidence in vaccination: a parent model. Vaccine. 2005;23:2486–2493. doi:10.1016/j.vaccine.2004.10.026 [CrossRef]
- Leask J, Kinnersley P, Jackson C, Cheater F, Bedford H, Rowles G. Communicating with parents about vaccination: a framework for health professionals. BMC Pediatr. 2012;12:154. doi:10.1186/1471-2431-12-154 [CrossRef]
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- Opel DJ, Taylor JA, Mangione-Smith R, et al. Validity and reliability of a survey to identify vaccine-hesitant parents. Vaccine. 2011;29:6598–6605. doi:10.1016/j.vaccine.2011.06.115 [CrossRef]
- Dube E, Laberge C, Guay M, Bramadat P, Roy R, Bettinger J. Vaccine hesitancy: an overview. Hum Vaccin Immunother. 2013;9:1763–1773. doi:10.4161/hv.24657 [CrossRef]
- Gust DA, Kennedy A, Shui I, Smith PJ, Nowak G, Pickering LK. Parent attitudes toward immunizations and healthcare providers the role of information. Am J Prevent Med. 2005;29:105–112. doi:10.1016/j.amepre.2005.04.010 [CrossRef]
- Domachowske JB, Suryadevara M. Practical approaches to vaccine hesitancy issues in the United States: 2013. Hum Vaccin Immunother. 2013;9:2654–2657. doi:10.4161/hv.26783 [CrossRef]
- Allison MA, Dunne EF, Markowitz LE, et al. HPV vaccination of boys in primary care practices. Acad Pediatr. 2013;13:466–474. doi:10.1016/j.acap.2013.03.006 [CrossRef]
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- Jacobson RM, Targonski PV, Poland GA. A taxonomy of reasoning flaws in the anti-vaccine movement. Vaccine. 2007;25:3146–3152. doi:10.1016/j.vaccine.2007.01.046 [CrossRef]
- Brunson EK. How parents make decisions about their children’s vaccinations. Vaccine. 2013;31:5466–5470. doi:10.1016/j.vaccine.2013.08.104 [CrossRef]
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