Expert at Sheba Medical Center says jab raises COVID antibody levels, but there are ‘still a lot of infections’ among those who received it ----- Nearly a month after Sheba Medical Center launched a landmark study to test the efficacy of a fourth COVID shot, the hospital said Monday that this fourth booster was only partially effective in protecting against the Omicron strain. “The vaccine, which was very effective against the previous strains, is less effective against the Omicron strain,” Prof. Gili Regev-Yochay, a lead researcher in the experiment said. “We see an increase in antibodies, higher than after the...