A drug called molnupiravir, which is used to treat Covid-19, may be driving the evolution of the SARS-CoV-2 virus, according to a recent analysis. The study found around 900 viruses with distinctive patterns of mutation that likely arose in people being treated with molnupiravir. However, none of these viruses are considered variants of concern.
Molnupiravir works by inducing mutations in RNA viruses like SARS-CoV-2, which prevents them from replicating and eventually leads to their elimination. However, there is a risk that these mutated viruses could spread to others before being eliminated from a person's body.
Some biologists are concerned that the risk of mutagenic drugs like molnupiravir generating potentially dangerous new variants may outweigh their benefits. Animal studies have also suggested that molnupiravir may cause DNA mutations, which is why it is not given during pregnancy or to individuals trying to conceive or breastfeeding.
Despite these concerns, regulatory agencies in many countries, including the US and UK, have approved molnupiravir for treating Covid-19.
The analysis conducted by researchers at the Francis Crick Institute in London found several lines of evidence supporting their conclusions. Countries that began using molnupiravir in 2022 saw a rise in the number of viruses with the distinctive mutations associated with the drug. Additionally, the researchers were able to identify cases where the viruses sequenced in the UK came from individuals treated with molnupiravir.
However, it is still unclear whether these mutations could lead to the creation of dangerous new variants. The data from the analysis does not indicate the likelihood of this happening, but it is something that should be considered.
A spokesperson for the company that makes molnupiravir, Merck, stated that the study relies on circumstantial associations and that there is no documented evidence of transmission of the mutated viruses from treated patients. The US Food and Drug Administration (FDA) also reviewed the initial findings and stated that while it is plausible that molnupiravir could contribute to mutational patterns in SARS-CoV-2, a causal relationship has not yet been established.
Overall, the study does not change the FDA's risk assessment of molnupiravir or other treatments triggering the evolution of new variants. Conventional drugs and antibodies can also put pressure on viruses to evolve and evade treatment.