The World Health Organization (WHO) recently released Immunization Agenda 2030, which envisions “a world where everyone, everywhere, at every age, fully benefits from vaccines to improve health and well-being.”
The same report refers to widely acknowledged measures of immunization program performance.
Despite those remarkable successes, more than 20 million children over 1 year of age have not received the basic recommended vaccines. And the proportion of children immunized with the DTP3 vaccine worldwide has remained static in recent years.
Some combination of wealth and empowerment may lead to higher vaccination coverage.
These data highlight the persistence of vaccination inequality around the globe, with the COVID pandemic further highlighting our challenges in implementing vaccination programs and developing relevant vaccines for use across a range of communities.
To move forward, we must better understand the role of the social determinants of health—the environmental, socioeconomic, cultural, and political conditions in which we live that affect our health—on childhood vaccination and how these determinants affect access to vaccines.
The differences in vaccination coverage across countries and among specific groups and regions within countries is striking. Contributing to these variations—between countries and within countries—is the plight of vulnerable groups.2 When income and wealth, maternal education, child sex, residence, ethnicity, religion, and other structural factors function to limit or prevent access to critical health services, including immunizations,3 the reduction in vaccine uptake further compounds vulnerability.
Disparities in vaccination coverage can be uncovered using official government statistics or in data from the Demographic and Health Surveys (DHS) and Multiple Indicator Clusters Surveys (MICS).4 Both surveys provide detailed information about vaccines in a standardized way using nationally representative samples.
These surveys permit examination of vaccination disparities, including timeliness of vaccination,5 by urbanicity, wealth status, maternal education, and other socioeconomic variables.6
A recent study also found a connection between women’s empowerment and wealth on childhood vaccination.7 For women with the most wealth resources, having greater empowerment may be more impactful on vaccination. For women with access to more modest financial resources, a higher level of empowerment is required to influence child vaccination. This suggests that some combination of wealth and empowerment may lead to higher vaccination coverage.
The WHO recently listed vaccine hesitancy as one of the 10 leading threats to global health.8 Vaccine hesitancy can clearly influence vaccination uptake. A recent global study of vaccine hesitancy found it to be the strongest predictor of vaccine uptake.9
Ongoing work on vaccine hesitancy in a variety of locations is helping us further understand the variety of factors that contribute to hesitancy:
While access to vaccines remains a significant barrier to vaccine uptake, many of the same factors that influence access also affect hesitancy. Both access and hesitancy are related in complex ways to social determinants of health.
As a variety of COVID vaccines are distributed around the world, we have opportunities to understand more fully the phenomenon of vaccine hesitancy and its relationship—in each context—to the social determinants of health that lead individuals toward or away from access and toward or away from a decision to receive a vaccine.
Abram Wagner is research assistant professor of Epidemiology in the School of Public Health. He studies predictors of vaccine-preventable disease incidence, with a particular focus on vaccine hesitancy. Wagner’s research is targeted toward evidence-based programs and policies that work toward the control of a broad range of vaccine-preventable diseases.
Matthew L. Boulton is senior associate dean for Global Public Health and professor of Epidemiology at the School of Public Health and professor of Internal Medicine at Michigan Medicine. At the School of Public Health, Boulton is also director of the Office of Global Public Health and is the Pearl L. Kendrick Collegiate Professor of Global Public Health. He founded the school’s Office of Public Health Practice and was director of the Preventive Medicine Residency for 20 years. He is the current editor-in-chief of the American Journal of Preventive Medicine and, prior to joining the University of Michigan, spent 16 years in public health practice, including as the governor’s chief medical executive and state epidemiologist. Boulton’s research interests are in global health, infectious disease epidemiology, childhood vaccinations and vaccine preventable diseases, preventive medicine, and the health workforce.
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