Neutralization heterogeneity of United Kingdom and South-African SARS-CoV-2 variants in BNT162b2-vaccinated or convalescent COVID-19 healthcare workers

There are concerns about neutralizing antibodies (NAb) potency against the newly emerged VOC202012/01 (UK) and 501Y.V2 (SA) SARS-CoV-2 variants in mRNA-vaccinated subjects and in recovered COVID-19 patients. We used a viral neutralization test with a strict 100% neutralizing criterion on UK and SA clinical isolates in comparison with a globally distributed D614G SARS-CoV-2 strain. In two doses BNT162b2-vaccinated healthcare workers (HCW), despite heterogeneity in neutralizing capacity against the three SARS-CoV-2 strains, most of the sera harbored at least a NAb titer ≥ 1:10 suggesting a certain humoral protection activity either on UK or SA variants. However, six months after mild forms of COVID-19, an important proportion of HCW displayed no neutralizing activity against SA strain. This result supports strong recommendations for vaccination of previously infected subjects.