Hydroxychloroquine does not prevent Covid infections, Catalan study finds

Catalan researchers have advised against the use of hydroxychloroquine to prevent Covid-19 after a major study found no evidence that the drug helps prevent the disease or alleviates its symptoms.  

Hydroxychloroquine (HCQ), a drug commonly used to treat malaria, was repeatedly promoted by United States President Donald Trump as a "miracle" cure for the coronavirus, but subsequent clinical trials have debunked such claims.

The Catalan study, led by epidemiologists Bonaventura Clotet and Oriol Mitjà and published in the New England Journal of Medicine, has further strengthened the case against HCQ.

From March 17 to April 28, researchers contacted 2,314 people who in the previous week had a close contact with someone who tested positive for Covid-19—that is, they were less than 2 meters away, for at least 15 minutes.

One group received one dose of 800mg of hydroxychloroquine on the first day of the trial, followed by 400mg-doses in the next six days. The control group received no real treatment.

In the first group, 5.7% developed coronavirus, with a 18.7% transmission rate. In the control group, 6.2% people contracted the disease, with a 17.8% transmission rate.

The incidence of adverse events was higher in the hydroxychloroquine group than in the usual-care group (56.1% vs. 5.9%), but no treatment-related serious adverse events were reported.