A study published this week linked the COVID-19 antiviral molnupiravir to new coronavirus mutations, raising questions about whether the drug could lead to the evolution of potentially concerning strains in the future.
The drug works by causing mutations in the genetic information of the virus. So, if some people don’t fully clear the virus after treatment, “there could be the potential for onward transmission of molnupiravir-mutated viruses,” according to the study, which was published in the journal Nature.
Researchers looked at 15 million coronavirus genomes to analyze the timing and type of mutations. They found that mutations increased after molnupiravir, which is commercially known as Lagevrio, was distributed.
Study authors said the findings are important for regulators who assess the drug.
Cartoons on the Coronavirus
“Since molnupiravir was first proposed as a treatment for COVID-19, some people have asked whether it could make the evolution of variants of concern more likely,” Theo Sanderson, the lead author of the study and a researcher at the Francis Crick Institute in London, wrote on social media. “In some sense our data makes these concerns more concrete because it makes clear that treatment can result in viruses with significant numbers of molnupiravir-induced mutations that can: (A) still be viable, rising to dominance in the host, and (B) in some cases be transmissible.”
But he added that it’s “difficult to quantify exactly how molnupiravir-treatment might change the risk calculus” and that no evidence suggests the drug has so far produced more transmissible or more severe coronavirus strains.
Merck criticized the study, saying it relied on assumptions.
“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 timeframe of sequence collection in countries where molnupiravir is available to draw their conclusions,” the company said in a statement.
It added that the mutations were “uncommon and were associated with sporadic cases.”
The Food and Drug Administration first approved molnupiravir for emergency use in late 2021. It’s authorized as a coronavirus treatment for high-risk patients in more than 25 countries, but sales have declined as COVID-19 immunity increased from previous infection and vaccinations, leading to fewer severe cases.