RSVpreF Vaccine Found to Be Safe, Effective During Pregnancy

FRIDAY, April 7, 2023 (HealthDay News) -- Receipt of bivalent respiratory syncytial virus prefusion F protein-based (RSVpreF) vaccine during pregnancy is safe and effective for preventing RSV illness in infants, according to a study published online April 5 in the New England Journal of Medicine.

Beate Kampmann, M.D., Ph.D., from the London School of Hygiene and Tropical Medicine, and colleagues conducted an international phase 3 trial in which pregnant women at 24 through 36 weeks of gestation were randomly assigned to receive a single intramuscular injection of the RSVpreF vaccine (3,682 women) or placebo (3,676 women).

The researchers found that medically attended severe lower respiratory tract illness within 90 days after birth occurred in six infants of women in the vaccine group and 33 infants of women in the placebo group (vaccine efficacy, 81.8 percent), and within 180 days of birth, 19 cases and 62 cases, respectively, occurred (vaccine efficacy, 69.4 percent). Within 90 days of birth, medically attended RSV-associated lower respiratory tract illness occurred in 24 infants of women in the vaccine group and 56 infants of women in the placebo group (vaccine efficacy, 57.1 percent), although this difference did not meet the statistical success criterion. No safety signals were seen in maternal participants or in infants and toddlers up to 24 months of age. Groups were similar with respect to the incidences of adverse events reported within one month after injection or within one month after birth (13.8 percent of women and 37.1 percent of infants for the vaccine group and 13.1 and 34.5 percent, respectively, in the placebo group).

"RSVpreF vaccine administered during pregnancy was effective against medically attended severe RSV-associated lower respiratory tract illness in infants," the authors write.

Several authors disclosed financial ties to Pfizer, which developed the RSVpreF vaccine and funded the study.

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