Two doses of an mRNA COVID-19 vaccine in mothers reduces the risk of infants aged less than 6 months being hospitalized by COVID-19, according to a recent study.
COVID-19 has a high chance of leading to complications in infants too young to receive the vaccine. To combat risks, investigators studied the effects of transplacental transfer of antibodies from maternal vaccination.
Infants hospitalized from COVID-19 between July 1, 2021, and March 8, 2022, were enrolled in a case-control test-negative design alongside infants hospitalized without COVID-19. Case infants were compared with control infants during the delta and omicron variants, with over 500 case infants during omicron, over 300 during Delta, and over 500 control infants between both variants.
About 15% of case infants had been born to mothers who were fully vaccinated, compared to about 30% of control infants. Intensive care was needed in 113 of the case infants and 64 of the control infants. Two case units born to unvaccinated mothers died from COVID-19.
Maternal vaccination saw a 52% effectiveness against hospitalization from COVID-19 overall, 80% during the delta period, and 38% during the omicron period. Effectiveness was almost 70% in cases of maternal vaccination after the first 20 weeks of pregnancy, and 38% during the first 20 weeks of pregnancy.
Halasa NB, Olson SM, Staat MA, Newhams MM, Price AM, Pannaraj PS, et al. Overcoming Covid-19 investigators. maternal vaccination and risk of hospitalization for Covid-19 among infants. N Engl J Med. 2022;387(2):109-119. doi: 10.1056/NEJMoa2204399