Data from three trials posted yesterday show efficacy of the Novavax and Pfizer COVID-19 vaccines and good immune response of the Moderna vaccine against different SARS-CoV-2 variants of concern.Novavax versus B1351Two of the studies appeared in the New England Journal of Medicine (NEJM), the first of which describes a phase 2a-b clinical trial at 16 sites in South Africa from Aug 17 to Nov 25, 2020, on the efficacy of the Novavax COVID-19 vaccine against the B1351 variant first identified in South Africa, where virus transmission is ongoing.Led by scientists from Novavax, the study involved randomly assigning HIV-negative participants aged 18 to 84 years and medically stable HIV-positive participants aged 18 to 64 years in a 1:1 ratio to