Hydroxychloroquine pills (illustration image). – Ben Margot / AP / SIPA
Taking hydroxychloroquine shortly after being exposed to Covid-19 does not, in principle, prevent infection, researchers reported on Wednesday following a clinical trial.
The drug was touted by President Donald Trump, who said it was used as a preventative against coronavirus. But a study of 821 people in the United States and Canada found that it was not much more effective than a placebo for this purpose.
No “significant benefit of hydroxychloroquine”
A team of scientists led by the University of Minnesota selected adults who had been in contact with a coronavirus positive person for more than 10 minutes at a distance of two meters or less. The majority of them were considered “at risk” of being infected because they did not wear a mask or eye protection when interacting with the infected person.
All randomly received either hydroxychloroquine or a placebo within four days of contact. The researchers then analyzed through laboratory tests and the study of symptoms how many of them contracted Covid-19 in the following two weeks. “This randomized trial did not demonstrate a significant benefit from hydroxychloroquine as a prophylactic treatment after exposure to Covid-19,” concluded the authors.
49 of 414 patients (12%) who received treatment contracted the disease, compared to 58 of 407 (14%) who received a placebo, a difference not considered statistically significant. Side effects were more common with hydroxychloroquine than with placebo, but in both cases they were not undesirable.
No definitive answer
The results of the study were eagerly awaited as it was a randomized controlled trial, an experience which is considered the benchmark for the study of clinical outcomes. Long used against malaria, hydroxychloroquine, whose efficacy against Covid-19 has never been rigorously demonstrated, unleashes passion.
Despite everything, “the study is too small to be irrefutable,” warns Martin Landray, a professor of medicine and epidemiology at the University of Oxford, who was not involved in the preparation of the study. More studies will be needed to know for sure whether or not hydroxychloroquine can have a moderate positive effect, the expert said.
