Vaccine Hesitancy: What Research Shows About Causes and Effective Communication

Vaccine hesitancy, defined by the World Health Organization as the delay in acceptance or refusal of vaccination despite the availability of vaccine services, has been identified as one of the top ten threats to global health. While the vast majority of Americans accept recommended vaccines, a meaningful minority express hesitancy, and the COVID-19 vaccination campaign brought vaccine attitudes to unprecedented levels of public and political attention. Research on the psychological, social, and structural factors that drive hesitancy and on the communication strategies that improve vaccine acceptance offers guidance that is applicable across vaccines and populations. Vaccine hesitancy is not a single phenomenon but a spectrum of attitudes and behaviors. Research distinguishes among individuals who actively refuse vaccines, those who are uncertain and open to persuasion, those who delay vaccination for logistical rather than attitudinal reasons, and those who are fully accepting. The distribution across this spectrum varies by vaccine, population, and time period. Treating all non-vaccinated individuals as ideologically opposed to vaccination misses the majority, who are in the uncertain, delaying, or access-limited categories and who may be reached through different communication and access approaches. Psychological research has identified several belief structures associated with vaccine hesitancy. Concerns about vaccine safety are the most common driver across populations and vaccines. Distrust in pharmaceutical companies, government health agencies, and medical institutions is a related factor that shapes how individuals process information about vaccines. Perceived low risk of the disease the vaccine prevents affects the cost-benefit calculation that individuals make when deciding whether to vaccinate. Research on the structure of vaccine attitudes finds that these beliefs cluster in ways that predict hesitancy and that different belief profiles may respond to different communication approaches. Confidence in vaccine safety is shaped by both the actual safety record of vaccines and by trust in the institutions that produce, approve, and recommend them. Research on institutional trust finds that trust in public health agencies, physicians, and government health officials is the strongest predictor of vaccine acceptance across populations. Events that damage institutional trust, including high-profile cases of research misconduct, inadequate transparency about vaccine risks, and politically motivated interference in health agency recommendations, have lasting effects on vaccine attitudes that persist beyond the specific incident that produced them. Social networks and community norms are significant influences on vaccine attitudes and behavior. Research on social contagion of vaccine hesitancy finds that hesitant individuals cluster geographically and socially, and that attitudes toward vaccination spread through social networks. Communities with high social trust and strong local health leadership show higher vaccination rates than those with lower social cohesion. Research on the role of healthcare providers in vaccination decisions consistently finds that provider recommendations are the most influential factor in patient vaccination decisions, underscoring the importance of providers having confident, clear conversations about vaccines. Communication strategies for addressing vaccine hesitancy have been studied extensively, with findings that sometimes challenge intuitive approaches. Repeated assertion of vaccine safety without acknowledging the concerns that hesitant individuals have is associated with defensive entrenchment rather than attitude change. Research on motivational interviewing applied to vaccine hesitancy finds that approaches that explore individuals' concerns, acknowledge uncertainty where it exists, and respect autonomy while providing accurate information produce better outcomes than authoritative assertions that dismiss concerns. Presumptive communication, in which providers announce an appointment for vaccination rather than asking whether the patient wants it, has shown significant effectiveness in improving vaccination rates for childhood vaccines. Debunking, the practice of correcting vaccine misinformation, carries risks that research has documented. Studies find that repeating a false claim for the purpose of debunking it can inadvertently reinforce the claim in memory, particularly when the debunking is not memorable enough to override the initial false impression. Research on effective debunking recommends leading with the accurate information rather than the myth, explicitly flagging why the myth is wrong, and providing a plausible alternative explanation for why the myth gained traction. These principles have been incorporated into public health communication training. Trust in healthcare providers is a particularly important factor in communities with historical experience of medical racism and exploitation. Research on vaccine attitudes in Black communities documents higher hesitancy rates for some vaccines and identifies justified mistrust rooted in documented historical abuses including the Tuskegee Syphilis Study as a contributing factor. Communication strategies that acknowledge this history, demonstrate respect for community concerns, and engage community leaders as trusted messengers are more effective in these communities than approaches that ignore the historical context of medical mistrust. The most effective approaches to improving vaccination rates are those that combine convenient access with trusted communication. Research on access interventions including mobile vaccination clinics, workplace vaccination programs, and integrating vaccine offers into existing healthcare encounters finds significant impacts on uptake, particularly for populations that are vaccinated at lower rates due to logistical rather than attitudinal barriers. Combining access improvements with trusted community health worker outreach addresses both dimensions of hesitancy simultaneously.