IntroductionAs the SARS-CoV-2 pandemic disproportionately affects older adults, future pandemic vaccine response will rely on existing adult immunization infrastructures.
MethodsWe evaluated the 2018 WHO/UNICEF Joint Reporting Form on Immunization for country reports on adult immunization programs. We described countries with programs and used multivariable regression to identify independent factors associated with having them.
ResultsOf 194 WHO Member States, 120 (62%) reported having any adult vaccination program. The Americas and Europe had the most adult immunization programs, most commonly Hepatitis B and influenza vaccines (>45% and >90% of countries). Africa and South-East Asia had the fewest adult immunization programs, with <11% of countries reporting any adult immunization programs for influenza or hepatitis vaccines, and none for pneumococcal vaccines. In bivariate analyses, high- or upper-middle income, introduction of new or underused vaccines, having achieved pediatric vaccine coverage goals, and meeting National Immunization Technical Advisory Groups basic functional indicators were significantly associated (p<0.001) with having any adult immunization programs. In multivariable analyses, the factor most strongly associated with adult immunization programs was country income, with high- or upper-middle income countries significantly more likely to report having a program (aOR 19.3, 95% CI 6.5, 57.7).
DiscussionThat 38% of countries lack functional platforms for adult immunization has major implications for future SARS-CoV-2 vaccine deployment. Systems for vaccine storage and handling, delivery, and waste management for adult immunization do not exist in much of the world. Developing countries should strengthen immunization programs to reach adults with SARS-CoV-2 vaccines when they become available.
