Experts worry Merck COVID-19 pill may give rise to new mutations

A new preprint study found that Merck's COVID-19 pill, Lagevrio (molnupiravir), creates new mutations of the virus in some patients who take the drug, validating concerns scientists had warned about before it was authorized at the end of 2021, Bloomberg reported Feb. 1. 

The study, published Jan. 27 in the preprint server medRxiv, found mutations tied to the drug's use in viral samples from dozens of patients. None of the mutations linked to the drug have been shown to be more severe or immune-evasive. The findings hint at risks that may come with wider use of Lagevrio, recently cleared in China, according to scientists. 

"There's always been this underlying concern that it could contribute to a problem generating new variants," Jonathan Li, MD, a virologist at Boston-based Harvard Medical School and its teaching hospital, Brigham and Women's in Boston, told Bloomberg. "This has largely been hypothetical, but this preprint validates a lot of those concerns."

Merck's COVID-19 antiviral works by creating mutations in the virus's genome that keep the virus from replicating in the body to reduce the chances of severe disease. Merck disputes findings in the pre-print, citing limitations in the study's design. 

"Data from clinical trials has demonstrated that molnupiravir use results in a rapid decline in viral infectivity," the company said in a statement emailed to Becker's Feb. 2. "The authors of the Sanderson et al. pre-print based their research on divergent global database SARS-CoV-2 sequences capturing consensus mutations present at high frequency within the viral population. The authors assume these mutations were associated with molnupiravir treatment without evidence the viral sequences were isolated from treated patients, relying on circumstantial associations between viral sequence origin and timeframe of sequence collection in countries where molnupiravir is available to draw their conclusions. Furthermore, these sequences were uncommon, and were associated with sporadic cases. These data must be considered in the context of all available clinical and non-clinical molnupiravir data."

In the U.S., Lagevrio has emergency use authorization for adults who have COVID-19, are at high-risk of severe symptoms and when alternative therapies are not clinically appropriate.


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