Alliance for Pandemic Preparedness

February 16, 2021

Sensitivity of Infectious SARS-CoV-2 B.1.1.7 and B.1.351 Variants to Neutralizing Antibodies

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[Pre-print, not peer reviewed] The SARS-CoV-2 B.1.1.7 variant (first described in the UK) was experimentally shown to have similar sensitivity to the neutralizing activity of convalescent sera (n=83) collected up to 9 months post symptom onset compared to the wild-type virus. In contrast, neutralizing titers had a mean 6-fold reduction against the B.1.351 variant (first described in South Africa) and a loss of neutralizing activity in 40% of convalescent sera at 9 months post symptom onset. 

Among sera from 19 vaccinees collected at various timepoints during the vaccination regimen, neutralizing titers were lower against the B.1.1.7 variant and to a greater extent against the B.1.351 variant compared to the wild-type virus. After the second dose, at a 1/30 serum dilution, 80% of sera neutralized the wild-type and the B.1.1.7 variant but only 60% neutralized the B.1.351 variant.

No neutralizing activity against the wild-type virus and the variants was detected in the nasal swabs from the vaccinees 2-3 weeks post vaccination, except among 3 vaccinees who had a history of SARS-CoV-2 infection. Neutralizing activity was similar for the wild-type virus and B.1.1.7 variant, but was absent for the B.1.351 variant.

Planas et al. (Feb 12, 2021). Sensitivity of Infectious SARS-CoV-2 B.1.1.7 and B.1.351 Variants to Neutralizing Antibodies. Pre-print downloaded Feb 16 from https://doi.org/10.1101/2021.02.12.430472