- Molnupiravir is being given to thousands of vulnerable patients as treatment against Covid
- The antiviral drug, made by American pharmaceutical giant Merck, forces mutations in the virus
A Covid drug hailed as a game-changer and prescribed to more than 20,000 British patients could actually cause the virus to mutate, scientists warned today.
Molnupiravir is being given to thousands of vulnerable Britons who test positive, such as patients battling cancer or liver and kidney disease.
The antiviral drug, made by US pharmaceutical giant Merck, protects against serious illness by forcing mutations into the virus that fatally weaken it.
However, in some cases these mutations do not kill the virus, say researchers from the Francis Crick Institute and the UK Health Security Agency (UKHSA).
Instead, a patient can remain infected with a mutated version of Covid and pass it on to others, according to the team’s analysis of millions of virus sequences.
Molnupiravir showed effectiveness against the Omicron variant in laboratory studies
Experts have warned that it is now crucial to find out whether mutations caused by molnupiravir make the virus more transmissible or severe, or allow it to evade immunity from previous infections or vaccines.
Some have even warned that its use could lead to the emergence of new variants, although the manufacturer has allayed such fears.
Molnupiravir, sold under the brand name Lagevrio, works by stopping Covid from growing and spreading in an infected person, keeping virus levels low.
This helps the body’s immune system control the infection, reducing the risk of severe symptoms and hospitalization.
Clinical trials suggest the drug – which was rolled out to patients in Britain from December 2021 and is described as an ‘excellent addition’ to the country’s ‘arsenal against Covid’ – halves the risk of hospitalization or death from Covid.
The team, made up of scientists from the University of Cambridge, Imperial College London, the University of Liverpool and the University of Cape Town, noted that molnupiravir’s effects are the result of causing a series of mutations in the virus.
Many of the mutations damage or kill the virus.
However, in some patients the virus is not completely cleared, meaning they can infect others with the molnupiravir mutated virus.
They examined a family tree of 15 million Covid sequences collected from global databases to map the mutations over time.
Covid is constantly mutating and most have little to no effect on the properties of the virus, such as how transmissible it is or the severity of the infection it causes.
However, in a study published in the journal Nature, researchers said they noticed changes in the virus that looked very different from expected patterns.
These mutations were strongly linked to people who had taken molnupiravir.
The team noted that the frequency of these changes increased in 2022, as the rollout accelerated.
The unusual changes in the virus were also more common in older people – who are more likely to receive the drug – in countries known to have high molnupiravir use and in samples taken during clinical trials of the drug .
According to the researchers, three in 10 of the abnormal mutations observed in England were among those given the drug.