Scientists from University of Minnesota launched the trial March 22 to see if the drug could decrease the severity of symptoms and prevent hospitalization. Previous randomized clinical trials in the United States had looked at hydroxychloroquine as prevention, or as treatment for hospitalized coronavirus patients.
It was tested in 491 adults in the United States and Canada. Half the patients received five days of hydroxychloroquine treatment and half the patients received five days of a placebo. The adults were enrolled within the first four days of reporting symptoms, and 56% were enrolled in the trial the first day they reported any symptoms. Doctors monitored symptoms for two weeks.
At the end of two weeks, the study found that there was no advantage to taking the drug. About 24% of the hydroxychloroquine group had symptoms that persisted over 14 days, compared to the 30% who took the placebo. But hospitalizations were nearly the same — 2% of those in the hydroxychloroquine group were hospitalized, compared to the 3% taking the placebo. The death rate was identical for both groups, at 0.4%.
And, 43% of those who took hydroxychloroquine had side effects, compared to the 22% that took a placebo. Gastrointestinal symptoms were the most commonly reported side effect.
The study also found there was no benefit seen among people who took zinc or vitamin C along with the placebo or hydroxychloroquine.
The University of Minnesota researchers’ first randomized trial, published in the New England Journal of Medicine in June, looked at the drug as a possible post-exposure prophylaxis for adults who had been recently exposed to someone who had Covid-19. The study showed hydroxychloroquine did not prevent illness.
“Taken together, there is no convincing evidence that hydroxychloroquine can either prevent COVID-19 after exposure or reduce illness severity after developing early symptoms,” study author Dr. Caleb Skipper said in a press statement. “While disappointing, these results are consistent with an emerging body of literature that hydroxychloroquine doesn’t convey a substantial clinical benefit in people diagnosed with COVID-19 — despite its activity against the coronavirus in a test tube.”
A separate study also published on Thursday of 293 Covid-19 patients in Barcelona found similar results: Hydroxychloroquine did not benefit non-hospitalized patients with mild Covid-19.
President Donald Trump has repeatedly sung the praises of the drug and called hydroxychloroquine a “game-changer” for treating patients with Covid-19. He even said he took it himself to prevent infection.
Prescriptions for hydroxychloroquine and a related drug, chloroquine, skyrocketed in the United States from February to March, studies found.
But several studies have found no benefits to treating Covid-19 patients with the antimalarial drug. At least one study showed the drug was linked to heart problems.
The US Food and Drug Administration revoked its emergency use authorization for both hydroxychloroquine and chloroquine for the treatment of Covid-19, on June 15, saying the drugs are unlikely to be effective in treating the virus based on the latest scientific evidence. The US stockpile was then stuck with 63 million doses of hydroxychloroquine.
The National Institutes of Health announced last month it was halting its clinical trial of hydroxychloroquine for coronavirus patients. Physicians groups advised doctors to stop using it as a part of a treatment for Covid-19 patients.
One study published this month by researchers at Henry Ford Health System in Southeast Michigan found hydroxychloroquine increased hospitalized patients’ chances of survival. However, researchers not involved with the study were critical of it, saying it wasn’t of the same quality of the previous studies that showed hydroxychloroquine did not help patients.