Researchers published the results of the trial in the New England Journal of Medicine on Wednesday. The randomized, placebo-controlled trial tested if hydroxychloroquine could prevent COVID-19 infection in healthy persons after exposure to someone with COVID-19, according to a news release.
It was the first randomized clinical trial testing if the drug could be used for post-exposure
prevention of COVID-19.
The trial enrolled 821 non-hospitalized adults from across the U.S. and Canada, who were exposed to COVID-19 from someone living in their same household or as a healthcare worker or first responder. Half of the participants received five days of hydroxychloroquine while the other half received five days of a placebo. Participants were then followed for two weeks to see who developed symptomatic COVID-19.
The trial was a double-blind trial, meaning that neither the participants nor the researchers knew who received hydroxychloroquine or the placebo.
The trial results determined hydroxychloroquine was not able to prevent the development of COVID-19 any better than a placebo.
Researchers also found that 40 percent of trial participants taking hydroxychloroquine developed non-serious side effects—predominantly nausea, upset stomach or diarrhea. The trial found no serious side effects or cardiac complications from taking the drug.
Researchers had launched the trial with the hope that an inexpensive, widely-available, oral medication could prevent or treat COVID-19 early, before people become sick enough to need hospital care.
Last month, President Donald Trump announced he was taking hydroxychloroquine as a preventative measure against COVID-19.