Pfizer reports that the vaccine efficacy in infants born from mothers who received the RSV vaccine during the third trimester of pregnancy was 57.1 percent at 90 days after birth, but waned to 51.3 percent at 180 days and 41 percent at 360 days. Vaccine efficacy for severe RSV was reported at 81.8 percent at 90 days after birth, but waned to 69.4 percent at 180 days. Vaccine efficacy related to hospitalizations were reported to be 67.7 percent at 90 days after birth, but waned to 33.3 percent at 360 days.
