Pfizer and BioNTech have asked FDA to grant emergency use authorization for a fourth Covid-19 vaccine dose for people 65 and older amid fears of waning immunity ahead of a possible late spring wave of infections, the companies announced Tuesday.
The request for a second booster shot is based on two real-world data sets from Israel suggesting another vaccine dose boosts protection against the Omicron variant while maintaining its safety profile. It’s unclear whether that’s enough data for FDA to consider to amend the existing EUA, which allows one booster dose.
One tranche of data showed confirmed infection rates were two times lower, and rates of severe illness four times lower, among those who received a second booster at least four months after their first compared to people who only got one booster shot. And an ongoing clinical trial in health care workers in Israel showed that those who got a fourth vaccine dose at least four months after their first booster saw antibody levels increase seven- to eight-fold two to three weeks after the shot, compared to five months after the first booster. They also saw a corresponding increase in neutralizing antibodies against Omicron after the additional dose.