Merck's COVID Pill Linked to New Virus Mutations

New research reveals that Merck & Co.’s popular antiviral drug, molnupiravir, may be causing dangerous mutations of the SARS-CoV-2 virus making it more contagious and actually contributing to the spread of COVID-19. A recent preprint study claims that molnupiravir could be prolonging and fueling the COVID-19 pandemic by creating these mutant viruses.

This new information seems to back up the concerns of many researchers who have stated that the drug, brand name Lagevrio, may create more contagious or life-threatening variants of COVID-19, which has killed more than 6.8 million people globally over the past three years, says Bloomberg.

According to Science, virologist William A. Haseltine, chair of ACCESS Health International, has repeatedly raised concerns about the drug. “It’s very clear that viable mutant viruses can survive [molnupiravir treatment] and compete [with existing variants],” he said. “I think we are courting disaster.”

Merck’s spokesperson denied the fact their drug is responsible for creating a variety of mutations and other experts agree.

“Right now, it’s much ado about nothing,” says Raymond Schinazi, a medical chemist at the Emory University School of Medicine, adding that the SARS-CoV-2 virus is infecting millions of people worldwide and naturally mutating at a fast clip.

Molnupiravir was the first antiviral approved to fight COVID-19 in the U.K., and the U.S. in late 2021. It has since been authorized in dozens of other countries and in 2022, global sales of the drug topped $5 billion, says Merck. From the inception of the drug, Haseltine and others were suspicious about its mechanism. Molnupiravir works by producing so many mutations that the virus can no longer reproduce. But skeptics were concerned that the drug might mutate not only the coronavirus, but the DNA of people receiving it, says Science.

Virus hunters and scientists around the world began sequencing the specific mutations that may be caused by molnupiravir. The drug is more likely to cause nucleic substitutions in cells, with guanine switching to adenine and cytosine to uracil.

Ryan Hisner, a middle school science teacher from Monroe, Indiana, started to catalog the suspect variants in August 2022.  After raising his concerns on Twitter, he teamed up with Thomas Peacock, a virologist from Imperial College, London. The pair, along with other scientists and colleagues, reviewed more than 13 million SARS-CoV-2 sequences in the international GISAID database, the world’s largest repository for these sequences. In a preprint posted on January 27, they report that a large subset showed the hallmark substitutions which are all dated from 2022 after molnupiravir was widely used.

The signature clusters were 100 times more common in countries where molnupiravir was widely used, including the U.S., Australia, and the U.K. than in countries where it was not commonly used such as France and Canada.

“Clearly something is happening here,” said Peacock. But the researchers say that it is unknown whether the changes could lead to more transmissible or dangerous variants.  

“There’s always been this underlying concern that it could contribute to a problem generating new variants,” said Dr. Jonathan Li, associate professor of infectious diseases at Harvard Medical School. “This has largely been hypothetical, but this preprint validates a lot of those concerns.”

Merck disputes the view that its drug is problematic.

“There is no evidence to indicate that any antiviral agent has contributed to the emergency of circulating variants,” said Merck spokesperson Robert Josephson. “Based on available data we do not believe that Lagevrio (molnupiravir) is likely to contribute to the development of new meaningful coronavirus variants.”

Josephson pointed out that the study authors assume the mutations were associated with molnupiravir treatment, but don’t have direct proof that the mutations arose in patients who took their drug. He said that the researchers drew their conclusions from “circumstantial associations between viral sequence origin and timeframe of sequence collection in countries where molnupivar is available.”