published in the online journal Nature.
There’s no evidence that molnupiravir, sold under the brand name Lagevrio, has caused the creation of more transmissible or severe variants of COVID, the study says, but researchers called for more scrutiny of the drug.
Researchers looked at 15 million COVID genomes and discovered that hallmark mutations linked to molnupiravir increased in 2022, especially in places where the drug was widely used, such as the United States and the United Kingdom. Levels of the mutations were also found in populations where the drug was heavily prescribed, such as seniors.
Molnupiravir is an antiviral given to people after they show signs of having COVID-19. It interferes with the COVID-19 virus’s ability to make copies of itself, thus stopping the spread of the virus throughout the body and keeping the virus level low.
The study found the virus can sometimes survive molnupiravir, resulting in mutations that have spread to other people.
Theo Sanderson, PhD, the lead author on the study and a postdoctoral researcher at the Francis Crick Institute in London, told The Guardian that the implications of the mutations were unclear.
“The signature is very clear, but there aren’t any widely circulating variants that have the signature. At the moment there’s nothing that’s transmitted very widely that’s due to molnupiravir,” he said.
The study doesn’t say people should not use molnupiravir but calls for public health officials to scrutinize it.
“The observation that molnupiravir treatment has left a visible trace in global sequencing databases, including onwards transmission of molnupiravir-derived sequences, will be an important consideration for assessing the effects and evolutionary safety of this drug,” the researchers concluded.
When reached for comment, Merck questioned the evidence.
“The authors assume these mutations were associated with viral spread from molnupiravir-treated patients without documented evidence of that transmission. Instead, the authors rely on circumstantial associations between the region from which the sequence was identified and time frame of sequence collection in countries where molnupiravir is available to draw their conclusions,” the company said.
The Food and Drug Administration authorized the use of molnupiravir for the treatment of mild to moderate COVID-19 in adults in December 2021. The FDA has also authorized the use of nirmatrelvir/ritonavir (Paxlovid), an antiviral made by Pfizer.
A version of this article appeared on WebMD.com.