COVID vaccine efficacy against the B.1.351 (“South African”) variant—The urgent need to lay the groundwork for possible future challenge studies

Nir Eyal, Arthur Caplan, Stanley Plotkin

Publication Date: 04/27/2021

SARS-CoV-2’s B.1.351 (“South African”) variant “is markedly more resistant to neutralization by convalescent plasma (9.4 fold) and vaccinee sera (10.3–12.4 fold),”1,2 raising the specter that that variant could resist the leading authorized spike-based vaccines.2 Indeed, in earlier lab exams, Moderna’s vaccine showed “A six-fold reduction in neutralizing titers … with the B.1.351 variant relative to prior variants.”3 Pfizer-BioNTech’s “neutralization of the B.1.351-spike virus was weaker by approximately two thirds.”4 When tested in human volunteers, AstraZeneca’s vaccine provided only 10% protection from mild to moderate disease caused by that variant, and its distribution in South Africa was suspended.5 Janssen’s vaccine also did less well in South Africa than elsewhere, presumably due to lower neutralization of infecting viruses.