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Despite the marked efficacy of vector-based and mRNA vaccines against the SARS-CoV-2 spike (S) protein, emergence of the variants B.1.1.7 (UK), B.1.351 (South Africa), and P.1 (Brazil) have called into question the durability of current vaccines as well as passive therapeutic antibody therapies. Researchers employed a vesicular stomatitis virus vector system to generate particles with S proteins of wild-type and variant SARS-CoV-2. They then examined the efficacy against cellular entry of these viral particles (in human cell lines) of entry inhibitor molecules, therapeutic antibodies, and plasma from COVID-19 convalescents and BNT162b (Pfizer-BioNTech) vaccine recipients.
The monoclonal antibody imdevimab blocked entry of all viral variants, while casirivimab was effective against B.1.1.7 and partially effective against B.1.351 and P.1. Variants B.1.351 and P.1 were completely resistant to bamlanivimab. B.1.1.7 was blocked by all antibodies. Convalescent plasma from COVID-19 patients exhibited neutralizing activity against B.1.1.7, but less so against B.1.351 and P.1. The vast majority of plasma samples from vaccinated persons also showed limited neutralizing activity against B.1.351 and P.1, although all sera completely inhibited entry of wild-type SARS-CoV-2.
Hoffmann M et al. SARS-CoV-2 variants B.1.351 and P.1 escape from neutralizing antibodies. Cell 2021 Mar 20; [e-pub]. (https://doi.org/10.1016/j.cell.2021.03.036)
Comment
Although it's difficult to generate clinical and epidemiologic predictions from a study utilizing artificially designed viral vector systems, these results illuminate the potentially false sense of security generated by the current SARS-CoV-2 vaccines. Just as bacterial pathogens can develop antimicrobial resistance necessitating continued evolution of drugs to keep pace, and the dynamics of influenza require annual vaccine modifications, the COVID-19 pandemic likely will also require ongoing vaccine development (perhaps requiring a polyvalent approach). Preventive measures and therapeutics also remain essential as these results suggest COVID-19 may not be disappearing anytime soon.