Vaccine Mandates and Influenza Vaccination During the Pandemic

Abstract

OBJECTIVES To determine whether a state influenza vaccine mandate and elevated community coronavirus disease 2019 (COVID-19) severity affected a child’s probability of receiving an influenza vaccine during the 2020–2021 influenza season, given the child’s previous vaccination history. METHODS Longitudinal cohort study using enrollment and claims data of 71 333 children aged 6 months to 18 years living in Massachusetts, New Hampshire, and Maine, from a regional insurer. Schoolchildren in Massachusetts were exposed to a new influenza vaccine mandate in the 2020–2021 season. Community COVID-19 severity was measured using county-level total cumulative confirmed case counts between March 2020 and August 2020 and linked by zip codes. The primary outcome of interest was a claim for any influenza vaccine in the 2020–2021 season. RESULTS Children living in a state with a vaccine mandate during the 2020–2021 influenza season had a higher predicted probability of receiving an influenza vaccine than those living in states without a mandate (47.7%, confidence interval 46.4%–49.0%, vs 21.2%, confidence interval 18.8%–23.6%, respectively, for previous nonvaccinators, and 78.2%, confidence interval 77.4%–79.0%, vs 58.2%, confidence interval 54.7%–61.7%, for previous vaccinators); the difference was 6.5 percentage points greater among previous nonvaccinators (confidence interval 1.3%–11.7%). Previously vaccinated children had a lower predicted probability of receiving an influenza vaccine if they lived in a county with the highest COVID-19 severity compared with a county with low COVID-19 severity (72.1%, confidence interval 70.5%–73.7%, vs 77.3%, confidence interval 74.7%–79.9%). CONCLUSIONS Strategies to improve uptake of influenza vaccination may have differential impact based on previous vaccination status and should account for community factors.