A preliminary study conducted in Israel has shown that a fourth dose of COVID-19 vaccine can boost antibodies to higher levels compared to the third shot, but does not seem to be enough to prevent Omicron infection.

Sheba Medical Center in Israel gave the second booster shots in a trial to its staff and is evaluating the effect of the Pfizer booster jab among 154 people after two weeks and the effect of Moderna booster shot in 120 people after one week. These were compared to a control group that did not get the fourth jab. People who received the Moderna shot had previously been given three jabs of Pfizer vaccine. GiliRegev-Yochay, director of the infectious diseases unit at the hospital, said that the vaccines increased the number of antibodies, even slightly higher than the third dose; however, “..this is probably not enough for the omicron.” (CNBC – Reuters, January 17, 2022)