Emi Takashita et al.: Efficacy of Antiviral Agents against the SARS-CoV-2 Omicron Subvariant BA.2, in: New England Journal of Medicine Vol. 386, Issue 15 (April 14, 2022) pp. 1475-1477, online in: https://doi.org/10.1056/NEJMc2201933.
In their letter to the editor, the authors report on their study looking at the efficacy of monoclonal antibodies against the omicron subvariants. They conclude that both etesevimab and bamlanivimab have lost neutralizing activity against the omicron subvariant BA.2. Imdevimab, which had no neutralizing activity against BA.1, however, has neutralizing activity against BA.2. Casirivimab inhibited BA.2 but not BA.1 or BA.1.1. Tixagevimab and cilgavimab neutralized BA. 2 with a lower FRNT [focus reduction neutralization test]-50 value (the titer of monoclonal antibody required for a 50% reduction in the number of infectious foci), which was still higher than for the wild variant and other variants of concern (alpha, beta, gamma, and delta variants). Soltorovimab has even lower efficacy against BA.2 than the already low efficacy against BA.1 and BA.1.1 The sensitivity of BA.2 to remdesivir, molnupiravir, and nirmatrelvir was similar to that of the wild variant and other variants of concern. The authors conclude by calling for clinical trials to determine whether antiviral therapies are effective against BA.2 infections.