Efficacy of the ChAdOx1 nCoV-19 Covid-19 Vaccine against the B.1.351 Variant

RCT (n=2,026) found a two-dose regimen of the ChAdOx1 nCoV-19 (AZ) vaccine did not reduce mild to moderate Covid-19 due to the B.1.351 (South Africa) variant vs placebo (incidence >14 days after 2nd vaccine = 3.2% vs 2.5%, efficacy 21.9%, 95%CI -49.9 to 59.8%).

New England Journal of Medicine