Moshe Geva Rosso, 62 years old, receives a fourth dose of the coronavirus disease (COVID-19) vaccine after Israel’s Health Ministry approved a second booster for the immunocompromised, at Sheba Medical Center in Ramat Gan, Israel, December 31, 2021. REUTERS/Nir Elias A fourth dose of the COVID-19 vaccine increases the number of neutralizing antibodies, but the boost is probably not enough to provide protection against infection of the Omicron variant, findings of a preliminary study conducted by Israel’s Sheba Medical Center concluded. “We know by now that the level of antibodies needed to be protected from Omicron and not to get...