The blockbuster drug Merck developed to treat Covid-19 was linked to mutations that are transmitted when coronaviruses spread between patients. This finding will increase scrutiny over its effectiveness and the billions of dollars spent by governments to procure it.
Researchers analysed 15mn coronavirus sequences to determine which mutations occurred when. The results showed that they increased after the introduction of molnupiravir (also known as Lagevrio) in many countries in 2022.
Mutations were more common in people who took molnupiravir and were older, or at greater risk of serious disease. They were also more prevalent in countries that used the antiviral treatment more widely.
The findings raise questions about the efficacy of antiviral medications to treat Covid-19, as authorities prepare for an active autumn following a spike in cases caused by Omicron variants with many mutations.
Researchers from Imperial College London, Cambridge University, Liverpool University, Cape Town, and the UK Health Security Agency matched signatures in these mutations with those observed in drug trials.
Theo Sanderson is a postdoctoral research fellow at the Francis Crick Institute and the lead author of the study. He said that the findings are useful in assessing the risks and benefits of the drug. Theo Sanderson, lead author and postdoctoral researcher at the Francis Crick Institute said that this study was useful for assessing the drug’s risks and benefits.
Antiviral Medicines are designed to target viruses and prevent them from infecting healthy tissues, thereby helping the immune system fight infection. Molnupiravir is marketed by Merck, and developed in collaboration with US biotech company Ridgeback Biotherapeutics. It works by inducing tiny mutations within the virus.
The study was peer-reviewed, and published by Nature. It also suggested that there were small clusters mutations which were able transmit between patients. However, the genetic signature has not been linked to any variants currently of concern. The increase in cases is not linked to Omicron variants like BA. The use of molnupiravir is associated with the 2.86 strain.
As first reported 2022 molnupiravir was denied marketing authorization by the European Medicines Agency. It is now rarely used in western countries. Merck first contested the European regulator’s decision, but later retracted its appeal.
The Food and Drug Administration of the United States will approve emergency use by certain patient categories in late 2021.
Merck reported sales of more than $6bn in 2021-2022. This figure does not include sales made by generic companies on poorer markets.
Andrew Hill, senior visiting researcher at the Liverpool University’s pharmacology department, warned that this drug could also have side effects on pregnant women.
According to results from a UK clinical trial released last year, the drug did not show that it could reduce the risk of death and hospitalisation among adults who were at higher risk for the disease. Early-stage data had shown that molnupiravir could reduce the risk of hospitalisation or death by half. This figure was later revised down to around 30%.
Merck stated on Monday that they were “confident” about the clinical profile and limitations of the drug.