Merck’s COVID Anti-Viral Drug May Cause SAR-CoV-2 to Mutate

• by Natasha Hobley

• Published October 22, 2023
• Infections

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Scientists have found evidence to suggest that an anti-viral COVID-19 drug manufactured by Merck & Co. being used to treat COVID may be causing the SARS-CoV-2 virus to mutate and create new variants of the virus for which humans could have no immunity.¹

The mechanism of action of the drug molnupiravir, a pill also sold under the brand name Lagevrio, is to provoke errors in the virus’ genetic code to purposefully create mutations that will make the virus self-destruct.

However, publishing an article in Nature, scientists have reported finding evidence suggesting that, when SARS-CoV-2 survives in a person treated with the oral antiviral drug, it can lead to mutated versions of the virus that spread to other people. While those mutated variants are sometimes transmissible, it is unknown whether they are more dangerous. Scientists studying the phenomenon have noted that there is an increase in genetic diversity of the mutated coronavirus in the wild.¹

Theo Sanderson, PhD, lead author of a study looking into the relationship of molnupiravir and SARS-CoV-2 mutations, told The Guardian that his research demonstrates that the anti-viral pill “can give rise to significantly mutated viruses which remain viable.” Sanderson, who is a geneticist at London’s Francis Crick Institute, added that while none of the worldwide variants were caused by the drug, “it is very difficult to predict whether molnupiravir treatment could potentially lead to a new widely circulating variant which people don’t have prior immunity to.”²

Dr. Sanderson and his research team combed through databases containing more than 15 million SARS-CoV-2 genomes and then used the data to track changes in mutations of the virus in populations throughout the pandemic. They identified a specific “mutational signature” at certain regions of the virus’s genetic code in those treated with molnupiravir.

They found the hallmark mutations were more prevalent in countries that had used the most molnupiravir, such as the United States, Australia, the United Kingdom and Japan; however those mutations were  rare in countries where the drug was not approved, such as in Canada and France.² The SARS-CoV-2 mutations were more common in elderly populations treated with the antiviral drug.¹

Merck Refutes Anti-Viral COVID Drug Study Conclusions

Merck, the company that manufactures molnupiravir, said the anti-viral pill impairs viral replication and reduces shedding, which reduces the risk of transmission. They refuted the conclusions of the study, saying the researchers had relied on circumstantial associations… without documented evidence of that transmission.”²

Dr. Sanderson rebutted Merck’s accusation, stating the researchers used “several independent lines of evidence to identify with confidence that molnupiravir drives this mutational signature.”²

Merck’s Anti-Viral COVID Drug Under Emergency Use Authorization since 2021

In the U.S, molnupiravir was granted Emergency Use Authorization (EUA) by the U.S. Food and Drug Administration (FDA) in 2021 for patients with mild to moderate COVID symptoms, who are at risk of progression to severe complications, hospitalization and death.³ The anti-viral pill was originally developed to treat influenza.¹

Sales of molnupiravir topped $20 billion in 2022 but fell 82 percent in the second quarter of 2023 compared to the same period last year.²

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