On May 8, New York City physicians reporting in the New England Journal of Medicine tracked outcomes for almost 1,400 patients with severe COVID-19.
Hydroxychloroquine is safe for malaria, and conditions like lupus or arthritis, but no clinical trials have recommended the use of hydroxychloroquine for coronavirus. Early laboratory work suggested that they also have powerful antiviral properties.
Several small studies in Europe and China spurred interest in using hydroxychloroquine against Covid-19, but were criticised for lacking scientific rigor. President Trump in particular has touted the drugs by calling them a "game changer", even this week, telling reporters that he is taking hydroxychloroquine. "A couple of weeks ago I started taking it".
When asked about his reasons for taking the drug, Trump emphasised he believed "it's good, adding he "heard a lot of good stories", and that "a lot of frontline workers and doctors" take it". The US Food and Drug Administration in April issued a warning about its use.
Hydroxychloroquine and chloroquine got attention early on in the pandemic as a potential treatment for COVID-19, the disease caused by the novel coronavirus.
The drugs have now been shown to be tied to a greater risk of death and heart rhythm problems in the study of almost 100,000 patients around the world.
Today's large new study appears to reinforce those concerns and deflate exaggerated hopes.
Mehra and colleagues looked at the medical records of more than 96,000 COVID-19 hospitalized patients from 671 hospitals in various countries. Their average age was approximately 54 years, and approximately 54 percent were male.
The death rates of the treated groups were: hydroxychloroquine 18%; chloroquine 16.4%; control group 9%.
A massive study of 96,032 hospitalized coronavirus patients found that the antimalarial medications hydroxychloroquine and chloroquine didn't benefit the patients that took them.
Those who received chloroquine and a macrolide had a 37% higher risk of dying in hospital and a 301% higher risk of developing severe arrhythmia.
It found that those who were treated with chloroquine, hydroxychloroquine through four methods all died at a higher rate than those who did not received the drug.
"An association of increased overall mortality was identified in patients treated with hydroxychloroquine alone", the researchers wrote.
The clinical trial that is part of a study led by the Bangkok-based Mahidol Oxford Tropical Medicine Research Unit (MORU), supported by the University of Oxford and health charity Wellcome, will initially involve hospitals in Brighton and Oxford. As an observational study, it can not prove cause and effect; it only reveals associations with treatments.
Only one drug, Gilead Sciences Inc.'s remdesivir, has been shown to benefit coronavirus patients in a clinical trial.
While the researchers tried to adapt to the different risk factors of the patients, it is possible that other unmeasured factors influence the course of their diseases. Furthermore, the findings do not speak of risks or outcomes for patients who are not hospitalized with COVID-19 and have mild or asymptomatic infections.
So far, the COPCOV team says lab evidence showed these drugs might be effective in preventing or treating coronavirus, but there was no conclusive proof.
"This is the first large-scale study to find statistically robust evidence that treatment with chloroquine or hydroxychloroquine does not benefit patients with COVID-19", Dr. Mandeep Mehra, the study's lead author and medical director of the Brigham and Women's Hospital Heart and Vascular Center in Boston, said in a news release on Friday.