Hydroxychloroquine ineffective at preventing COVID-19

NEW YORK: Scientists have conducted a clinical trial that reported taking hydroxychloroquine shortly after being exposed to COVID-19 does not help prevent infection in a meaningful way.

The anti-malarial drug has been touted by US President Donald Trump who has said he used it as part of precautions against the novel coronavirus. However, an experiment involving 821 people across the United States and Canada showed it did not work significantly better than a placebo for this purpose.

The study was led by a team at the University of Minnesota and their paper was published in the New England Journal of Medicine. Researchers enrolled adults who had come into contact with someone who had a confirmed case of COVID-19 for more than 10 minutes at a distance of six feet or less.

The majority of them, 719 cases specifically, were deemed to have had ‘high-risk’ exposure because they wore neither a face mask nor an eye shield at the time. The rest were ‘moderate-risk’ because they covered their face but did not have goggles.

All participants were randomly assigned to receive either hydroxychloroquine or a placebo within four days. The researchers then looked at how many patients went on to develop COVID-19 over the next two weeks, which was confirmed either by a laboratory test or clinical signs.

They found that 49 of the 414 given the medicine got the disease caused by the coronavirus, compared to 58 of the 407 on the placebo. This translates to 11.83 percent on the drug were infected, versus 14.25 percent on the placebo.

The difference of about 2.4 percentage points in favour of the medicine was not considered statistically significant given the sample size, meaning it could have occurred by chance.

The side effects were more common with hydroxychloroquine than with the placebo – 40.1 percent versus 16.8 percent – but no serious adverse reactions were reported.

“This randomized trial did not demonstrate a significant benefit of hydroxychloroquine as postexposure prophylaxis for COVID-19,” the trial’s authors wrote.

The results of the study were eagerly awaited because it was a randomised controlled trial (RCT), a carefully designed experiment considered the gold standard for investigating clinical outcomes.

Several previous studies on the drug that have made headlines were observational, meaning they looked back at what had already happened. As such, more variables are left to chance and it is generally harder to draw firm conclusions.

Martin Landray, a professor of medicine and epidemiology at the University of Oxford, said more research was needed to know for sure whether hydroxychloroquine might have a moderately positive effect. Landray, who was not involved in the trial, said the study is too small to be definitive.