Maternal mRNA COVID-19 Vaccination During Pregnancy and Delta or Omicron Infection or Hospital Admission in Infants: Test Negative Design Study

( BMJ . 2023;380:e074035) Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) rates are higher in infants than in older children. Passive immunity has been shown to help prevent other infections, such as pertussis, in infants through the transfer of maternal antibodies following vaccination during pregnancy. SARS-CoV-2 antibodies are found to be present in breastmilk, umbilical cord blood, and infant serum specimens following maternal vaccination during pregnancy and infection, and emerging research suggests maternal COVID-19 vaccination reduces infant infection and hospital admission rates. This study aimed to determine whether maternal vaccination during pregnancy with 2 primary doses or 2 primary doses plus booster of the mRNA COVID-19 vaccine series reduces the infection of omicron and delta SARS-CoV-2 and hospital admission of infants within 6 months following delivery.