
A fourth shot of COVID-19 vaccine boosts antibodies to even higher levels than the third jab but it is not enough to prevent Omicron infections, according to a preliminary study in Israel.
Israel's Sheba Medical Center has given second booster shots in a trial among its staff and is studying the effect of the Pfizer booster in 154 people after two weeks and the Moderna booster in 120 people after one week, said Gili Regev-Yochay, director of the Infectious Diseases Unit.