The currently dominant Omicron variant BA.2 can spread faster than the already highly contagious BA.1 variant, the authors say. It is therefore essential to validate the efficacy of drugs already known and used to treat COVID disease against this new variant. These laboratory tests confirm the effectiveness of the antivirals remdesivir, molnupiravir and the active ingredient of the pill Paxlovid (nirmatrelvir/ritonavir) as well as that of certain monoclonal antibodies, such as Evusheld from AstraZeneca. But of certain antibodies only.
Overall lower effectiveness of current drugs
These in vitro laboratory experiments, conducted on cells of non-human primates, tested 7 monoclonal antibodies, 3 combinations of antibodies and the 3 antivirals against the BA.2 variant. Most clinically approved antibody treatments are actually combinations of several antibodies. These tests show that:
- the intravenous drug remdesivir and the active ingredients of 2 anti-COVID-19s, Paxlovid and molnupiravir are almost as effective against BA.1 as against the original strain of SARS-CoV-2;
- the most effective antibody therapy against the BA.2 variant is Evusheld, which is approved for prophylaxis against COVID-19 infection in people at risk for severe disease;
- other antibodies such as etesevimab/bamlanivmab, used together as a single treatment fail to neutralize the BA.2 virus at common doses in these laboratory tests. Finally, other antibody treatments prove less effective against BA.2 than against earlier strains of SARS-COV-2.
Thus, without being totally negative, taken together, these results warn against a lesser effectiveness of certain anti-COVID treatments available against the new variants. Which makes sense, as these treatments have been tested or designed against earlier versions of the virus.
New drugs will therefore have to be developed against the new variants, a process that takes months, the researchers point out.