Randomized trial shows hydroxychloroquine has no benefit over placebo in preventing COVID-19

Hydroxychloroquine sulfate tablets
Randomized trial shows hydroxychloroquine has no benefit over placebo in preventing COVID-19. Credit: © amlanmathur - Depositphotos

Today, University of Minnesota Medical School researchers published the results from the first randomized clinical trial testing hydroxychloroquine for the post-exposure prevention of COVID-19.

The trial results, which were published in the New England Journal of Medicine, determined that hydroxychloroquine was not able to prevent the development of COVID-19 any better than a placebo. Further, 40% of trial participants taking hydroxychloroquine developed non-serious side effects — predominantly nausea, upset stomach or diarrhea. However, the trial found no serious side effects or cardiac complications from taking hydroxychloroquine.

The randomized placebo-controlled trial, which rapidly launched on March 17, tested if hydroxychloroquine could prevent COVID-19 infection in healthy persons after exposure to someone with 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. The trial was a double-blind trial, meaning that neither the participants nor the researchers knew what the participants received. Participants were followed for two weeks to see who developed symptomatic COVID-19.

Overall, approximately 12% of those given hydroxychloroquine developed COVID-19 versus approximately 14% given the vitamin placebo (folate). This was not a statistical difference, and even if there was a statistical difference, this would equate to treating 42 persons with hydroxychloroquine in order to prevent one infection. There was no further benefit to prevent infection among those who also took zinc or vitamin C.

David Boulware, MD, MPH, the senior investigator of the trial and infectious disease physician at the University of Minnesota, launched the trial with the hope that an inexpensive, widely-available, oral medication could prevent or treat coronavirus early in the disease before people are sick enough to need hospital care.

“Our objective was to answer the question of whether hydroxychloroquine worked to prevent disease or did not work,” Boulware said. “While we are disappointed that this did not prevent COVID-19, we are pleased that we were able to provide a conclusive answer. Our objective was to find an answer.”


Materials provided by the University of Minnesota Medical School. Content may be edited for clarity, style, and length.


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