Role of vaccine age restrictions on rotavirus vaccine coverage, Vaccine Safety Datalink 2018—2024

Background Rotavirus vaccines (RVs) are coadministered in the United States with diphtheria-tetanus-acellular pertussis (DTaP) vaccines but have age restrictions for the first and last doses. We examined how delays in preventive care visits for vaccination affected RV initiation and series completion. Methods We compared the timeliness of DTaP vaccination relative to RV in children born January 1, 2018 to June 30, 2023 across eight U.S. health systems. Adjusted risk ratios (aRR) were estimated using modified Poisson regression to identify risk factors for delayed DTaP vaccination and no RV vaccination. Results Among 391,892 children who initiated DTaP, 12,546 (3.2%) did not initiate RV. Of these, 7,721 (61.5%) children had delayed DTaP initiation and were age-ineligible for RV at the time of DTaP initiation. Children who became eligible for RV during the early stage of the COVID-19 pandemic (March–May 2020) had a higher risk of delayed DTaP and no RV initiation (aRR = 2.20; 95% CI 1.98–2.45), as did children with fewer than five primary care visits within the first year of life (aRR = 4.03; 95% CI 3.81–4.26), and Medicaid recipients (aRR = 2.34; 95% CI 2.23–2.45). Similar factors were associated with failure to complete the RV series due to age restrictions. Conclusions Age restrictions may have contributed to lack of RV initiation and series completion in this cohort. Public health strategies tailored to populations at risk for delayed vaccination may be needed to promote timely administration of RV.