The study was led by a team from the University of Minnesota. (File)
Washington, United States:
Taking hydroxychloroquine soon after being exposed to COVID-19 does not help prevent infection in a statistically significant way, scientists reported on Wednesday after a clinical trial.
The drug was touted by U.S. President Donald Trump, who said it was used as prophylaxis against the new coronavirus.
But an experiment involving 821 people across the United States and Canada has shown that it doesn’t work much better than a placebo for this purpose.
The study was led by a team from the University of Minnesota and their article was published in the New England Journal of Medicine.
Researchers enrolled adults who had contacted someone who had a confirmed case of COVID-19 for more than 10 minutes at a distance of six feet (about two meters) or less.
The majority of them – 719 – were considered to have had a “high risk” exposure because they wore neither a face mask nor an eye mask at the time, while the others were “moderate risk” because they covered their faces but had no glasses.
All participants were randomized to receive either hydroxychloroquine – which is certified for use against malaria, rheumatoid arthritis and lupus – or placebo, within four days.
The researchers then looked at the number of patients who developed COVID-19 in the next two weeks, which was confirmed either by a laboratory test or by clinical signs.
They found that 49 of 414 receiving the drug had coronavirus disease, compared to 58 of 407 on placebo.
This translates to 11.83% for the infected drug, compared to 14.25% for the placebo.
The absolute difference of approximately 2.4 percentage points in favor of the drug was not considered statistically significant given the sample size, which means that it could have occurred due to chance.
Side effects were more common with hydroxychloroquine than with placebo – 40.1% versus 16.8% – but no serious side effects were reported.
“This randomized trial did not demonstrate a significant benefit of hydroxychloroquine as a post-exposure prophylaxis for COVID-19,” wrote the authors.
The results of the study were eagerly awaited as it was a randomized controlled trial (RCT), a carefully designed experiment that is considered the gold standard for studying clinical outcomes.
Several previous drug studies that hit the headlines were “observational,” meaning they looked back at what had already happened. As such, more variables are left to chance and it is generally more difficult to draw firm conclusions.
Nevertheless, Martin Landray, professor of medicine and epidemiology at the University of Oxford, said that more research was needed to know for sure whether hydroxychloroquine could have a moderately positive effect.
“The study is too small to be final,” said Landray, who was not involved in the trial.
The results “make it very unlikely that there is a significant effect (for example, a halving of the risk of infection) but cannot exclude a more modest difference (for example a reduction of a quarter or a that would still be very useful. “, he added.
