This is an advance summary of a forthcoming article in the Oxford Research Encyclopedia of Global Public Health. Please check back later for the full article.
Vaccination is one of the greatest public health successes. With sanitation and clean water, vaccines are estimated to have saved more lives over the past 100 years than any other health intervention. Vaccination not only protects the individual, but also provides, in many instances, community protection against vaccine-preventable diseases through herd immunity. To reduce the risk of vaccine-preventable diseases, vaccination programs rely upon reaching and sustaining high coverage rates. Paradoxically, because of the success of vaccination, new generations are unaware of the risks of these serious diseases, and their concerns now concentrate on the perceived risk of individual vaccines. Public health experts are increasingly concerned about resistance to vaccination. Over the past decades, several vaccine controversies have occurred worldwide, generating concerns about vaccine adverse effects and eroding trust in health authorities, experts, and science. Widespread public acceptance of vaccines can no longer be taken for granted. Gaps in vaccination coverage can be attributed, in part, to vaccine hesitancy and not just to “supply side issues” such as access to vaccination services and affordability.
The concept of vaccine hesitancy is now commonly used in the discourse around vaccine acceptance. The World Health Organization defines vaccine hesitancy as “lack of acceptance of vaccines despite availability of vaccination services. Vaccine hesitancy is complex and context specific, varying across time, place, and vaccines.” Vaccine hesitancy contributes to a deeper understanding of vaccination decisions by moving beyond the traditional binary of pro- or anti-vaccine attitudes to recognize a spectrum of beliefs and associated behaviors that occupy the space between the two poles. A vaccine-hesitant person can delay, be reluctant, but still accept or refuse one, some, or all vaccines. Technical, psychological, sociocultural, political, and economic factors can contribute to vaccine hesitancy. Vaccination decisions are complex and multidimensional, and can be very vaccine-specific. At the individual level, recent reviews have focused on factors associated with vaccination acceptance or refusal, identifying determinants such as fear of side effects, perceptions around health and prevention of disease and a preference for “natural” health, low perception of the efficacy and usefulness of vaccines, negative past experiences with vaccination services, and lack of awareness or knowledge about vaccination. The World Health Organization summarizes the diverse factors leading vaccine hesitancy under three broad categories: complacency, convenience, and confidence.
Very few interventions have been effective in reducing vaccine hesitancy. Most of the studies have only focused on metrics of vaccine uptake and refusal to evaluate interventions aimed at enhancing vaccine acceptance, which makes it difficult to assess their potential effectiveness to address vaccine hesitancy. In addition, despite the complex nature of vaccination decision making, the majority of public health interventions to promote vaccination are designed with the assumption that vaccine hesitancy is due to lack of or inadequate knowledge about vaccines (“knowledge-deficit” approach). Simply communicating evidence of vaccine safety and efficacy to those who are vaccine-hesitant has done little to stem the growth of hesitancy-related beliefs and fears, however. A key predictor of acceptance of a vaccine by a vaccine-hesitant person remains the recommendation for vaccination by a healthcare provider. When providers communicate effectively about vaccine benefits and risks, the value and need for vaccinations and vaccine safety, people are more confident in their decisions. However, to do this well, healthcare providers must be confident themselves about the safety, effectiveness, and importance of vaccination. Recent research has shown that a proportion of healthcare providers are vaccine-hesitant in their professional and personal lives, and effective strategies to address vaccine hesitancy among these providers have yet to be identified. A better understanding of the dynamics of the underlying determinants of vaccine hesitancy is critical for effective tailored interventions to be designed for the public and for healthcare providers.