The USA has recently approved two antimalarial drugs to treat COVID-19. But a new study has found that they may not be effective at fighting off the virus.

Results from a small clinical trial in France, published in the French medical journal, Médecine et Maladies Infectieuses, found that the drugs did not appear to help the immune system clear coronavirus from the body.

The research included 11 patients who were in hospital with COVID-19. Each received the drugs, hydroxychloroquine and azithromycin. After 5-6 days of treatment, the virus was still present in the body. These results are different to a previous study that found the virus had cleared from the body after 5-6 days of treatment with the same drugs.

Both studies had very small numbers of people who were given the drugs and so bigger studies are needed.

An expert working in the field of antiviral research has raised concerns about the drugs. Future President of the International Society for Antiviral Research, Professor Katherine Seley-Radtke, has written an opinion article that urges caution against the use of the drugs before there is enough evidence to show if they are effective.