8 April — New coronavirus variants muscle aside potent antibodies
Fast-spreading coronavirus variants identified in California blunt the antibody response triggered by vaccines.
In early 2021, researchers studying coronaviruses collected in California spotted a pair of SARS-CoV-2 variants that share several mutations affecting the spike protein, which the virus uses to infect cells. The variants, B.1.427 and B.1.429, have been identified in 30 countries and most US states and, by February 2021, accounted for more than half of the SARS-CoV-2 viruses sequenced from California.
To better gauge any threat posed by the variants, David Veesler at the University of Washington in Seattle and his colleagues conducted laboratory tests of the variants’ ability to elude infection-blocking molecules called neutralizing antibodies (M. McCallum et al. Preprint at bioRxiv https://doi.org/f5jq; 2021). The tests showed that neutralizing antibodies generated by people who had received two doses of either the Pfizer or the Moderna vaccine were, on average, three times less potent against viruses with the spike-protein mutations found in B.1.427 and B.1.429 than against viruses lacking those mutations. The findings have not yet been peer reviewed.
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Xiaoying Shen and David Montefiori at Duke University in Durham, North Carolina, and their colleagues conducted a separate investigation into how B.1.429 responds to antibodies (X. Shen et al. N. Engl. J. Med. https://doi.org/f5kc; 2021). The team pitted the variant against neutralizing antibodies from three sources: people immunized with the Moderna vaccine, people immunized with a vaccine made by Novavax and people who had recovered from COVID-19. Laboratory tests showed that B.1.429 was more resistant to inhibition by all three sets of antibodies than was a strain of the virus that circulated earlier in the pandemic.
The reductions in antibody potency are similar to those observed with a variant called B.1.1.7, which was first identified in the United Kingdom. Current vaccines are highly effective against B.1.1.7, suggesting that they are likely to remain so against the variant identified in California, Montefiori’s team says