To examine the association between influenza vaccination during pregnancy and infant influenza vaccination.
We conducted a retrospective analysis of individuals aged 15–49 years who were continually privately insured from August 2017 to May 2019 and had singleton live births between September 2017 and February 2018 and their infants. Influenza vaccination coverage was assessed for pregnant people during the 2017–2018 influenza season and for their infants during the 2018–2019 season using the 2017–2019 MarketScan data. Multivariate log-binomial regressions were conducted to examine the association between influenza vaccination during pregnancy and infant influenza vaccination.
Of the 34,919 pregnant people in this analysis, 14,168 (40.6%) received influenza vaccination during pregnancy. Of the infants born to people vaccinated during pregnancy, 90.0% received at least one dose of influenza vaccine during the 2018–2019 season and 75.5% received at least two doses. Of the infants born to those not vaccinated during pregnancy, 66.3% received at least one dose of influenza vaccine and 51.8% received at least two doses. At-least-one-dose coverage was 35.7% higher (adjusted risk ratio [aRR] 1.34, 95% CI 1.33-1.36) and at-least-two-dose coverage was 45.8% higher (aRR 1.43, 95% CI 1.41-1.46) for infants born to people who received influenza vaccination during pregnancy compared with infants born to people who did not.
Our results show a positive and statistically significant relationship between influenza vaccination during pregnancy and infant influenza vaccination status in their first season eligible for vaccination. Interventions to increase influenza vaccination coverage among pregnant people may also increase infant influenza vaccination coverage, offering greater protection against serious complications of influenza in both vulnerable populations.