(HealthDay News) — Maternal vaccination with mRNA vaccine during pregnancy is associated with a reduced risk for hospitalization for COVID-19 among infants younger than 6 months, according to a study published online June 22 in the New England Journal of Medicine.
Natasha B. Halasa, M.D., from the Vanderbilt University Medical Center in Nashville, Tennessee, and colleagues assessed the effectiveness of maternal vaccination during pregnancy against hospitalization for COVID-19 among infants younger than 6 months. Infants hospitalized for COVID-19 (case infants) and infants hospitalized without COVID-19 (control infants) at 30 hospitals in 22 states were enrolled. Vaccine effectiveness was estimated by comparing the odds of full maternal vaccination among case and control infants during circulation of the delta variant (July 1 to Dec. 18, 2021) and the omicron variant (Dec. 19, 2021, to March 8, 2022). Data were included for 537 case infants (181 and 356 admitted during the delta and omicron periods, respectively) and 512 control infants.
The researchers found that 16 and 29 percent of the case and control infants, respectively, had been born to mothers who had been fully vaccinated against COVID-19 during pregnancy. Twenty-one percent of the case infants received intensive care and two died from COVID-19; neither infant’s mother had been vaccinated during pregnancy. The effectiveness of maternal vaccination was 52 percent against hospitalization for COVID-19 among infants: 80 and 38 percent during the delta and omicron periods, respectively. Effectiveness was 69 versus 38 percent when maternal vaccination occurred after 20 weeks of pregnancy versus during the first 20 weeks.
“These findings provide additional support for the current recommendations regarding COVID-19 vaccination during pregnancy,” the authors write.
Several study authors disclosed financial ties to the biopharmaceutical industry.