The first high-quality study of malaria pill hydroxychloroquine just found it doesn't help prevent coronavirus infections

AP Photo/David J. PhillipA doctor holds a bottle of hydroxychloroquine.
  • The malaria drug hydroxychloroquine doesn’t help prevent coronavirus infections in people who were recently exposed to the virus, study results set to be published Wednesday show.
  • It’s the first high-quality trial to test the malaria pills as a preventive treatment. More than 800 volunteers were randomly assigned to take hydroxychloroquine or a placebo.
  • “If you’re the general public, if you’re the president or anyone, and you’re exposed to somebody with known COVID, taking this is not going to reduce your risk of developing infection,” Dr. David Boulware, the lead researcher on the study, told Business Insider.
  • Hydroxychloroquine has devolved into a political issue, as President Donald Trump has repeatedly touted the drug as a game-changer and said he took it to prevent infection.
  • Visit Business Insider’s homepage for more stories.

Taking hydroxychloroquine does not help prevent coronavirus infections for people recently exposed to the virus, results from a new study show.

The findings come from one of the first high-quality trials to test the malaria pills that have been repeatedly promoted by President Donald Trump. Infection rates were about the same for people taking hydroxychloroquine or a placebo. The study is set to be published Wednesday in The New England Journal of Medicine.

It is a major blow for the theory that hydroxychloroquine has some antiviral effects that could combat the coronavirus. A growing body of evidence now suggests the generic medication does not help infected people, but this is the first high-quality study to test if hydroxychloroquine prevents infections.

As the coronavirus outbreak spread across the globe, doctors raced to identify existing medications like hydroxychloroquine that might be able to help patients, often relying on anecdotal reports and test-tube studies. More than a dozen other drugs, such as the failed Ebola pill remdesivir and the arthritis treatments Actemra and Kevzara, are also being evaluated as coronavirus treatments.


Read more: Drugmakers are racing to find ways to treat the novel coronavirus by repurposing existing medications. Here’s what you need to know about remdesivir and 15 other leading treatments.

Dr. David Boulware, an infectious disease researcher at the University of Minnesota, led the study of hydroxychloroquine, which has been widely used as a lupus and arthritis treatment for many years. It was first approved in the 1950s to treat malaria.

In an interview with Business Insider, Boulware said hydroxychloroquine should not be used as a post-exposure preventive therapy, based on the results.

Open questions about hydroxychloroquine

“This trial is fairly conclusive that there is not a benefit for post-exposure prophylaxis,” Boulware said. “If you’re the general public, if you’re the president or anyone, and you’re exposed to somebody with known COVID, taking this is not going to reduce your risk of developing infection.”

Trump said he started taking the pills shortly after his valet became infected. The results suggest the pills wouldn’t help protect the president.


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There are still open questions about hydroxychloroquine, Boulware said. The first is whether it can help prevent coronavirus if it’s given regularly to healthy people who don’t have a known exposure to a virus. It is also still being studied as a treatment for coronavirus patients in the very first days of showing symptoms.

Boulware is involved in additional trials that test hydroxychloroquine in both of these setting. Those studies have recently wrapped up, and results should be publicly available within the next few weeks, he estimated.

Other studies are still ongoing with hydroxychloroquine as a COVID-19 treatment. The World Health Organisation reopened its hydroxychloroquine study Wednesday. The public health group had suspended it after a study raised safety concerns. The data used by that study is now in question.


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More side effects and the same amount of infections for people taking hydroxychloroquine

Plaquenil hydrochloroquine chloroquine drugs covid-19 coronavirusChesnot/Getty ImagesA French pharmacy worker holding a pack of hydroxychloroquine.

In mid-March, Boulware’s team began recruiting volunteers across the US and Canada. Participants filled out an online survey and were shipped the pills and monitored remotely if they qualified for the study.

People had to have been exposed to someone with a confirmed case of COVID-19 within four days. They were not eligible if they already had symptoms. The objective was to see if hydroxychloroquine can prevent COVID-19 infections in a high-risk group.

Volunteers and the researchers didn’t know who got the drug and who got a placebo. The study randomly assigned 821 people to either a five-day regimen of hydroxychloroquine or placebo.

The researchers tracked both groups, who routinely filled out online surveys about their health. Approximately 12% of people taking hydroxychloroquine got COVID-19 compared to 14% of the placebo group, according to a University of Minnesota press release. The difference was not statistically significant.

However, one finding was meaningful between the two groups: those taking hydroxychloroquine had much higher rates of side effects. About 40% on hydroxychloroquine registered side effects compared to 17% on placebo. These were mild reactions – most commonly nausea, diarrhoea, or vomiting – with no reported serious side effects.


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Boulware’s research unexpectedly got caught up in politics

Trump Dr. Anthony Fauci coronavirusAPPresident Donald Trump and Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases.

Boulware was among a handful of scientists looking into hydroxychloroquine, launching his study a few days before it first caught the attention of Trump. The president’s spotlight on the medication largely didn’t help, Boulware said.

“The vast amount of attention was not helpful in any sense of the word,” he said. It was difficult to enroll people into the study by early April as it rapidly became a partisan issue, he said.

The politicization led many people to make up their minds on whether the drug works, despite a lack of quality data, he said. Boulware said hydroxychloroquine’s supporters felt his study was unethical because it used a placebo group. Since they believed the pills were an effective treatment, they felt it would be unethical to withhold them from some people.

On the other side, sceptics thought the Minnesota study was equally unethical because it used hydroxychloroquine. A lot of that pushback resulted from Trump’s embrace of the drug, Boulware said. In particular, many believed it posed grave safety risks, particularly with anecdotal reports of serious heart problems.

It wasn’t just Trump who politicized the drug, he added. As New York City became the epicentre of the pandemic, local leaders encouraged widespread emergency use of hydroxychloroquine to treat COVID-19. But this was done ad hoc, instead of through an organised clinical trial that could collect results.

“That was more a political decision than a scientific decision,” Boulware said. “A scientific decision would be let’s have a large randomised trial to see if it works.”

Boulware’s study shows both groups were wrong on some counts. The pills weren’t effective in preventing infections. They also weren’t dangerous to take, with researchers reporting no serious side effects and no cardiac problems, such as arrhythmias, strokes, or heart attacks.

The safety concerns could vary across different groups of patients. Boulware’s study gave hydroxychloroquine alone to healthy people. In other cases, the drug is being used in combination with azithromycin to treat severely ill COVID-19 patients in the hospital.

Azithromycin carries a risk of affecting the heart’s rhythm, and the risk may be intensified by using the drug together with hydroxychloroquine.

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