The antiviral therapies remdesivir, molnupiravir and the active ingredient in Pfizer’s Paxlovid pill (nirmatrelvir) remain effective in laboratory tests against the BA.2 variant of SARS-CoV-2, the virus that causes COVID-19.
The BA.2 variant also remains sensitive to at least some of the monoclonal antibodies used to treat COVID-19, such as AstraZeneca’s Evusheld. However, the antibodies etesevimab and bamlanivmab, which are used together as a single treatment, were unable to neutralize the BA.2 virus at common doses in these laboratory tests. Other antibody treatments were less effective against BA.2 than against earlier strains of SARS-COV-2.
These findings come from new research led by Yoshihiro Kawaoka, a virologist at the UW School of Veterinary Medicine and the University of Tokyo. The BA.2 omicron variant is related to the more common BA.1 omicron virus, and some evidence suggests that BA.2 can spread faster than the already highly contagious BA.1 variant.
“At the end of the day, we have antibodies that seem to be more effective against BA.2 compared to BA.1 or BA.1.1. That’s good news, but we don’t know if what we found in the lab translates to the clinical setting. “, explains Kawaoka, who has previously tested the response of the BA.1 variant to treatments. “We have also tested clinically available antiviral compounds, and they are all very effective. »
Kawaoka and his collaborators at UW-Madison and the National Institute of Infectious Diseases in Tokyo published their findings in the New England Journal of Medicine March 9.
In lab experiments using cells from non-human primates, Kawaoka’s team tested seven monoclonal antibodies, three antibody combinations, and three antiviral treatments against the BA.2 variant. Most clinically approved antibody treatments are a combination of several antibodies.
The intravenous drug remdesivir and the active ingredients of two anti-COVID-19 pills, Paxlovid and Merck’s molnupiravir, were almost as effective against BA.1 as against the original strain of SARS-CoV-2.
The most effective antibody treatment against the BA.2 variant was Evusheld, which is approved in the United States to help prevent COVID-19 infection in people at risk for serious illness. Antibodies sold by Regeneron and GlaxoSmithKline were much more effective against BA.2 than against the BA.1 omicron variant, although they were not as potent against BA.2 as against earlier versions of the virus.
Available anti-COVID treatments are generally less effective against newer variants than against the original virus strain, because they were designed and tested against older versions of the virus. Researchers and pharmaceutical companies can design and test treatments against new variants, but this process takes months.
This work was supported in part by the National Institutes of Health (grants HHSN272201400008C and 75N93021C00014). The study was also supported by Japan Research Program on Emerging and Re-emerging Infectious Diseases (Grants JP20fk0108412, JP21fk0108615 and JP21fk0108104), Drug Discovery Support Project (Grant JP20nk0101632), Japan Research and Development Program Infrastructure on Infectious Diseases (Grant JP21wm0125002), and a Grant for Emerging and Re-emerging Infectious Diseases from the Ministry of Health, Labor and Welfare of Japan (Grant 20HA2007).
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Materials provided by The University of Wisconsin-Madison. Original written by Eric Hamilton. Note: Content may be edited for style and length.