Concordance Between Maternal and Infant COVID-19 and Influenza Vaccination Status

In this study, we evaluated whether maternal COVID-19 and influenza vaccination status during pregnancy was associated with infant vaccine coverage.

This observational cohort study included infants 6 to 13 months old born at Kaiser Permanente Northern California between August 2021 and March 2024 and their mothers. We used the Kaplan-Meier approach to estimate the cumulative probability of infants receiving at least one dose of a vaccine and Cox models to estimate the hazard ratio of infant vaccination by maternal vaccination status adjusted for covariates. Mothers were considered vaccinated if they received a COVID-19 or influenza vaccine from 12 months before pregnancy onset date to 3 months postpartum; those who did not receive a vaccine in this window were considered unvaccinated.

The study included 82 533 mother-infant pairs. Infants in the study had a 23.4% probability of receiving a COVID-19 vaccine and 66.2% probability of receiving an influenza vaccine in the first year of life. Infants whose mother received a COVID-19 vaccine during pregnancy were 9.65 (95% CI, 9.06-10.27) times more likely to be vaccinated against COVID-19 and those whose mother received an influenza vaccine during pregnancy were 3.67 (95% CI, 3.58-3.77) times more likely to be vaccinated against influenza than those whose mother was not vaccinated. Vaccination before pregnancy or during postpartum was also associated with infant vaccination compared with no maternal vaccination.

Maternal vaccination for respiratory vaccines was strongly associated with infant vaccination; increasing maternal vaccine coverage may improve infant coverage.