Vaccine Access and Vaccine Hesitancy Are Two Sides of the Same Coin

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.

• Over 1 billion children globally have been vaccinated in the last decade.
• 125 member states of the United Nations have each achieved 90% coverage with 3 doses of the diphtheria-tetanus-pertussis (DTP3) vaccine.¹

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:

• Patterns of socioeconomic disparities in vaccination coverage point to increases in vaccine hesitancy in wealthier individuals.
• Religious dimensions to vaccine equity and vaccine hesitancy could be emerging, for example in Indonesia.
• Comparative studies of parental hesitancy, for example comparing findings from the Parent Attitudes about Childhood Vaccines study in the US with findings about parental vaccine hesitancy in Shanghai, China. Notably in Shanghai, these concerns were more highly prevalent among the most recent migrants from rural areas into the city.

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.

Notes

1. Immunization Coverage, World Health Organization, July 2021.
2. Arsenault, C et al. "An Equity Dashboard to Monitor Vaccination Coverage." Bulletin of the World Health Organization 95 (2017):128-134.
3. Boyce T, et al. "Towards Equity in Immunisation." Eurosurveillance 24/2 (Jan 2019)
4. Cata-Preta BdeO, Wehrmeister FC, Santos TM, Barros AJD, Victoria CG. “Patterns in Wealth-Related Inequalities in 86 Low- and Middle-Income Countries: Global Evidence on the Emergence of Vaccine Hesitancy.” American Journal of Preventive Medicine 60/1s1 (2021):S24–S33.
5. Masters NB, Wagner AL, Boulton ML. “Vaccination Timeliness in Low- and Middle-Income Countries: A Systematic Review of the Literature, 2007–2017.” Human Vaccines and Immunotherapeutics 15 (Jun 2019):2790-2805. 
6. For example, a study by Mutua et al. used DHS results from 40 countries in Sub-Saharan Africa and found timely vaccination coverage to be <50%, although there were substantial variations across countries, from Burundi with 59.3% timely coverage to South Sudan with 2.5%. The authors also found that most countries, outside of Rwanda, Congo, and the Democratic Republic of Congo, had substantial disparities, with urban children from wealthier families whose mothers had higher education levels being more likely to be vaccinated in a timely manner.
7. Porth JM, Wagner AL, Moyer CA, Mutua MK, Boulton ML. “Women’s Empowerment and Child Vaccination in Kenya: The Modifying Role of Wealth.” American Journal of Preventive Medicine 60/1, S1 (Jan 2021):S87–S97.
8. Ten Threats to Global Health in 2019. World Health Organization.
9. de Figueiredo A, Simas C, Karafillakis E, Paterson P, Larson HJ. “Mapping Global Trends in Vaccine Confidence and Investigating Barriers to Vaccine Uptake: A Large-Scale Retrospective Temporal Modelling Study.” Lancet 396/10255 (Sept 2020):898-908.

About the Authors

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.