How effective are BIVALENT boosters at ⤵️ing HOSPITALIZATION / DEATH from Omicron (includes XBB.1.5) ? Disappointing findings from NEJM: 2 weeks 67 % effective 10 weeks 44 % 20 weeks 38 % https://www.nejm.org/doi/full/10.1056/NEJMc2302462#.ZEHur4iq_Vk.twitter