Bulletin of the Atomic Scientists reports:

A drug used to treat patients at risk of severe COVID-19 infection may have led to the emergence of SARS-CoV-2 viruses bearing a distinct pattern of mutations, researchers reported Monday in Nature. The new paper raises the stakes over concerns about whether molnupiravir use could lead to the emergence of new dangerous variants and extend the pandemic.

Molnupiravir, which is sold as Lagevrio, works by mutating SARS-CoV-2 and causing changes that should knock out the virus’s functionality. The mutated viruses aren’t supposed to replicate further, but researchers who looked at more than 15 million viral genome sequences found that a recognizable pattern of mutations emerged in 2022, when several countries began using the drug. They found this pattern in sequences from countries that used molnupiravir and in the age groups likely to have used the medication.

“We definitively demonstrate that molnupiravir has resulted in viable SARS-CoV-2 viruses with significant numbers of mutations, in some cases with onwards transmission of mutated viruses,” wrote Theo Sanderson, a fellow at The Francis Crick Institute in London and one of the new study’s authors. [Continue reading…]