A Covid drug that has just been approved in virus-stricken China causes the coronavirus to mutate in new ways, a study warns. 

US and UK researchers identified the new mutations in viral samples taken from dozens of patients given Merck’s antiviral Lagevrio.

The alterations to the virus did not make it more deadly or infectious, but the experts say it undermines the risk of drugs that work by tinkering with Covid’s genetic code.

While Lagevrio has rarely been used in the US or UK, it has just been authorized for use in China, where officials have been relying on poor vaccines and treatments amid a devastating wave of the virus. 

One expert warns this use can lead to the emergence of new variants – and even called the continued use of Lagevrio in some parts of the world ‘disturbing’.

Officials had been warning for months that sky-high infection rates in China – with experts fearing 250million infections struck the nation in December alone – could give rise to a dangerous new variant. And that was before the latest findings.

Merck's antiviral pill molnupiravir, sold under the name Lagevrio, may be causing Covid to mutate. While the detected mutations are not believed to be dangerous, there are fears that more changes to the virus now could open the door to future problems (file photo) Merck's antiviral pill molnupiravir, sold under the name Lagevrio, may be causing Covid to mutate. While the detected mutations are not believed to be dangerous, there are fears that more changes to the virus now could open the door to future problems (file photo)

Merck’s antiviral pill molnupiravir, sold under the name Lagevrio, may be causing Covid to mutate. While the detected mutations are not believed to be dangerous, there are fears that more changes to the virus now could open the door to future problems (file photo)

Concerns Lagevrio could spur mutations arose around the time it received authorization from the Food and Drug Administration (FDA) in late 2021. 

The drug works by creating mutations in the Covid genome that prevent the virus from replicating in the body.

While it was initially seen as a breakthrough, Pfizer’s Paxlovid overtook Lageviro as the Covid antiviral of choice worldwide, sidelining Merck’s drug for the past year.

The latest study has been published online as a pre-print and has not been peer-reviewed.

The team – which included experts from the Francis Crick Institute, Imperial College London and the University of Cambridge – looked at 13million RNA sequences of the virus that causes Covid.

They analyzed the nucleic makeup of RNA strands to search for indications the virus mutated because of the drug.

In hundreds of samples, they found evidence the drug had caused replication. Nearly all of the detections were in samples gathered in 2022 – the year it was made available worldwide – indicating Lagevrio is at fault.

‘It is possible that some patients treated with molnupiravir might not fully clear SARS-CoV2 infections, with the potential for onward transmission of molnupiravir-mutated viruses,’ researchers wrote.

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Merck, based in Rahway, New Jersey, disputed the report – saying there is no evidence it contributed to Covid variants, or could do so in the future.

‘Data from clinical trials has demonstrated that molnupiravir use results in a rapid decline in viral infectivity,’ a Merck spokesperson told DailyMail.com.

‘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.’

The results raise the possibility of future worrying strains of the virus emerging, experts fear.

Some experts immediately flagged the potential for the drug to cause worrying mutations when it first made headlines in late-2021.

Dr Richard Ebright, a molecular biologist at Rutgers University, in New Brunswick, New Jersey, was among those experts – warning against the drug’s use last year.

He told DailyMail.com Thursday: ‘Use of molnupiravir in any nation will contribute to the emergence of new variants of SARS-CoV-2.

‘In view of the poor – essentially zero–efficacy of molnupiravir against SARS-CoV-2, and in view of the high mutagenic activity of molnupiravir and its contribution to the emergence of new variants of SARS-CoV-2, it is disturbing that molnupiravir is being used anywhere, at any time, for the treatment of SARS-CoV-2.’

Dr William Haseltine, known as one of the world’s leading experts in human genome analysis, warned in late 2021 the way the drug worked opened the door to danger.

‘You are putting a drug into circulation that is a potent mutagen at a time when we are deeply concerned about new variants,’ he told Forbes.

He added: ‘I can’t imagine doing anything more dangerous.

‘If I were trying to create a new and more dangerous virus in humans, I would feed a subclinical dose [of molnupiravir] to people infected,’ he continued.

The drug was authorized for use by the FDA in December 2021. The approval was controversial among some experts because of the concerns about virus mutations.

It did show the ability to reduce hospitalizations and deaths from the virus by 50 percent in clinical trials, though. 

Shortly after, Pfizer’s Paxlovid received approval. With a higher 90 percent efficacy against hospitalizations and deaths – and without many of the concerns about virus mutations – the latter quickly became America’s Covid-fighting drug of choice.

While molnupiravir received little use in much of the western world, generic versions of it were used across less-developed countries.

It was also often used to treat Covid patients in Australia. 

It has also recently started have been used by Chinese officials to control Covid – which experts wholly disagree with.

There were even fears in 2021 that the vaccines themselves could spur the mutation of viruses.

Because of the immunity gap – where a majority of the population is vaccinated but there is still a small unvaccinated portion remaining – the virus could find a way to mutate around protection from the shots.

This did occur, as the vaccine-resistant Omicron strain emerged at the end of 2021. 

U.S. FDA removes COVID test requirements for Pfizer, Merck pills

The U.S. Food and Drug Administration (FDA) on Wednesday removed the need for a positive test for Covid-19 treatments from Pfizer Inc and Merck Co Inc .

Pfizer’s Paxlovid and Merck’s Lagevrio pills were given emergency use authorizations in December 2021 for patients with mild-to-moderate Covid, who tested positive for the virus, and who were at risk of progressing to severe Covid.

Still, the FDA said the patients should have a current diagnosis of mild-to-moderate Covid infection.

The health regulator said individuals with recent known exposure with signs and symptoms may be diagnosed by their healthcare providers with Covid even if they have a negative test result.

– Reuters