The updated efficacy rate results from 34 study participants, according to Pfizer.
Four infant cases showed a vaccine efficacy rate of 75.8 percent and nine cases among children aged between 2 and 4 found a 71.8 percent efficacy rate.
The FDA and CDC initiated emergency use authorization for Pfizer’s vaccine for the youngest population June 17, and Moderna’s vaccine for children 6 months to 5 years old was authorized the same day. Pfizer’s data at that time — before omicron subvariants BA.4 and BA.5 surged — showed an 80 percent efficacy rate. Moderna reported a 50.6 percent efficacy rate for infants 6 to 23 months old and a 36.8 percent efficacy rate for 2- to 5-year-olds.
As omicron subvariant BA.5 accounts for a high proportion of national cases, Pfizer is steaming ahead to gain federal approval of its tweaked vaccine booster aimed at BA.5.
