Safeway pharmacist Shahrzad Khoobyari (R) administers a Pfizer COVID-19 booster shot into Chen Knifsend’s arm at a immunization booster clinic on October 01, 2021 in San Rafael, California.
Justin Sullivan | Getty Images
A fourth vaccination with Covid-19 raises antibodies to even higher levels than the third vaccination, but this is not enough to prevent Omicron infections, according to a preliminary study in Israel.
Israel’s Sheba Medical Center has given second boosters among its staff in a trial and is studying the effect of Pfizer’s booster in 154 people after two weeks and Moderna’s booster in 120 people after one week, said Gili Regev-Yochay, director of the unit for infectious diseases.
These were compared to a control group that did not receive the fourth injection. The members of the Moderna group had previously received three vaccinations from Pfizer, the hospital said.
The vaccines resulted in an increase in the number of antibodies “even slightly higher than after the third dose,” Regev-Yochay said.
“Still, that’s probably not enough for the Omicron,” she told reporters. “We now know that even if it’s a good vaccine, the level of antibodies needed to protect and avoid contagion from Omicron is probably too high for the vaccine.”
The results, which the hospital said are the first of their kind in the world, are preliminary and have not yet been published.
Israel was the fastest country to roll out first vaccinations against Covid a year ago and last month began offering a fourth vaccination, or second booster, to the most vulnerable and high-risk groups.