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Anti-malaria drug hydroxychloroquine does little to prevent COVID-19, trial finds

Jeremy Olson, Star Tribune (Minneapolis) on

Published in News & Features

An anti-malaria drug that has been trumpeted as a therapy for COVID-19 was unable in a University of Minnesota clinical trial to prevent the onset of the infectious disease.

The results of the nation's first randomized trial with the drug, hydroxychloroquine, against COVID-19 will disappoint doctors who had hoped for new therapies against the pandemic. Many prescribers had given it off-label to COVID-19 patients -- in the absence of other options -- and President Donald Trump had been an early champion of the drug and disclosed in mid-May that he was taking it for the preventive benefit that the university study could not verify.

"While we are disappointed that this did not prevent COVID-19, we are pleased that we were able to provide a conclusive answer," said Dr. David Boulware, the leader of the University of Minnesota trial. "Our objective was to find an answer."

Results, published Wednesday in the New England Journal of Medicine, showed little difference in the onset of COVID-19 in 414 people who took hydroxychloroquine and a comparison group of 407 that took only vitamins. All participants had at least moderate risk for COVID-19 due to being exposed to others in their homes or workplaces who had the illness.

There was a small difference, as only 11.8% of people taking the drug developed COVID-19, compared to 14.3% of those taking vitamins, the study showed. However, that difference was considered statistically insignificant.

Even if valid, the small difference means that 42 people would have to take the drug prophylactically to prevent one COVID-19 case. That would be costly and expose people to drug side effects. The study showed that 40% experienced mild side effects such as nausea, but it also allayed fears that widespread use of the drug could result in more severe cardiac and other complications.


The study only provides evidence of whether the drug is effective in preventing COVID-19 onset. A separate University of Minnesota trial is examining whether it treats COVID-19 in patients after early onset of symptoms, but results haven't been published yet.

Enthusiasm for the drug has already tamped down following open-label trials and case reports from around the world that found little benefit, but the publication of the University of Minnesota results was a significant advance in the course of the pandemic. COVID-19 is caused by a novel coronavirus for which there is no vaccine.

Doctors said trial data was badly needed in the current anxious, politicized environment over COVID-19 and this drug. A study in the Journal of the American Medical Association last week showed a twentyfold surge in prescriptions of hydroxychloroquine and a similar drug, chloroquine, in late March after the World Health Organization declared a COVID-19 pandemic and the president issued a March 19 tweet in favor of the drug.

Surges based on hype threaten the supply of the drug for approved treatments of rheumatoid arthritis and lupus, said Dr. Frank Rhame, a virologist at Allina Health, adding that many doctors in March were issuing their first prescriptions of the drug and had no experience with it.


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