Hydroxychloroquine has been shown to be ineffective in preventing infection in people exposed to coronavirus, according to a widely anticipated clinical trial from the US.

The trial in the New England Journal of Medicine also found no serious side effects or heart problems from hydroxychloroquine use.

In the first major study comparing hydroxychloroquine to a placebo to gauge its effect against COVID-19, researchers tested 821 people who had recently been exposed to the virus or lived in a high-risk household.

It found 11.8% of those given the anti-malaria drug developed symptoms compatible with coronavirus, compared with 14.3% who received the placebo.