Anti-COVID drug accelerates viral evolution

Nature Molnupiravir, an antiviral drug used to treat COVID-19, induces numerous mutations in the SARS-CoV-2 genome that can increase the rate at which the virus evolves — yielding viral variants that might survive and be passed on. Drugs are potent weapons against viral pathogens. During the early stages of the COVID-19 pandemic, there were intensive efforts to discover and implement antiviral drugs that could treat SARS-CoV-2 infections, either by reducing the intensity of symptoms or by shortening the duration of infection. One of the drugs identified as part of that work was molnupiravir. Writing in Nature, Sanderson et al.¹ provide the most convincing evidence yet that molnupiravir-induced mutations in the SARS-CoV-2 genome can lead to new transmissible viral variants. Although there is no reason to think that any SARS-CoV-2 variant arose as a result of treatment with molnupiravir, public-health authorities should exercise caution when considering the therapeutic use of this drug and others that work in a similar way.