The malaria drug hydroxychloroquine has not prevented Covid-19 in a rigorous study of 821 people exposed to patients infected with the virus, researchers from the University of Minnesota and Canada reported on Wednesday.
The trial was the first controlled clinical trial of hydroxychloroquine, a drug that President Trump has repeatedly advertised and recently taken himself. This study, conducted in the United States and Canada, was the first to test whether the drug could prevent disease in people who were exposed to the coronavirus. This type of study, in which patients are randomly selected to receive either experimental treatment or placebo, is considered the most reliable way to measure the safety and effectiveness of a drug. The participants were health care workers and those exposed to sick spouses, partners or parents at home.
“The takeaway message for the general public is that if you are exposed to someone with Covid-19, hydroxychloroquine is not an effective post-exposure preventive therapy,” said the study’s lead author, Dr. David R. Boulware, from the University of Minnesota, said in an interview.
The results are published in the New England Journal of Medicine.
“If we could find something that would alleviate, block, or soften the infection after a solid exposure, it would be wonderful,” said Dr. Judith Feinberg, the vice chair for medical research at West Virginia University. “We want to limit the number of cases. There was great hope of riding on it. “
The president’s advertising for the drug and the backlash have politicized medical questions that would normally have been left to researchers to objectively answer. Trump supporters and opponents have accused each other of twisting facts about the drug so that the president looks either right or wrong.
But Mr. Trump hasn’t stopped announcing the potential benefits of the drug. His government announced on Sunday that it would send 2 million doses of the drug to Brazil to treat patients and prevent infections among healthcare workers. A White House official said the two countries would work together to research its use.
At the beginning of the pandemic, drug use was fueled by individual reports from China and France about patients who appeared to be improving, and laboratory findings about a possible antiviral effect. Since there is no proven treatment for Covid-19, doctors wanted to give therapy to critically ill patients.
Data from recent studies were questioned In the past week there have been further debates about the role of the drug in studies around the world. On Wednesday, the World Health Organization announced that it would temporarily resume studies due to data used in a study at the Lancet.
Interest in the drug grew after Mr. Trump began to advocate it. It is approved for the treatment of rheumatoid arthritis and lupus as well as malaria and is considered safe for these patients as long as they have no underlying abnormalities in their heart rhythm.
Studies in very sick coronavirus patients have linked the drug – especially in combination with the antibiotic azithromycin – to dangerous cardiac arrhythmias both the Food and Drug Administration and the National Institute of Allergy and Infectious Diseases have warned that it should not be used outside of clinical trials or carefully monitored hospital settings.
Some researchers say safety concerns about the drug have been exaggerated, which has alarmed the public and made it difficult to recruit participants for the studies needed to determine if the drug has value for treatment or prevention.
The new study included 821 people from the United States and parts of Canada who were either exposed to high or medium risk to people who tested positive and who had the coronavirus. None of the participants had symptoms themselves. High-risk exposure meant that they were less than a meter from a patient for more than ten minutes and had neither a mask nor face protection. A moderate risk meant that they wore a mask, but no face protection.
Around 88 percent were at high risk.
The participants recruited online were between 33 and 50 years old, with an average age of 40 years. Around half were women and 66 percent of the total were health care workers. They were healthy and had no underlying health problems that made hydroxychloroquine dangerous for them. Most of the rest had been exposed to an infected spouse, partner or parent at home.
Within four days of exposure, participants were randomly selected to receive either hydroxychloroquine or a placebo, and then determined whether they had either laboratory-confirmed Covid-19 or a virus-consistent disease for the next 14 days .
The drug or placebos were sent to them and they reported their symptoms online to researchers who did not examine them.
Not all participants could be tested for the virus because test kits were still lacking when the study was conducted.
There was no significant difference between the placebo group and those taking the drug. Among those who took hydroxychloroquine, 49 out of 414 or 11.8 percent got sick. In the placebo group, 58 or 407 or 14.3 percent became ill. Statistically analyzed, the difference between these rates was not significant.
The drug also made the disease no less serious.
Side effects such as nausea from hydroxychloroquine were more common than from placebos, 40.1 percent compared to 16.8 percent, but there were no heart rhythm problems or other serious side effects.
Infectious disease experts who did not take part in the study said it was well done and answered an important question, although the results were disappointing.
Dr. William Schaffner, an infectious disease specialist at Vanderbilt University, said: “This was a large, randomized, controlled trial conducted by very good people. Hydroxychloroquine offered no significant benefit. “
Dr. Schaffner found that the drug had shown some ability to prevent infection of cells by the virus in laboratory studies, and said, “Unfortunately, this did not have a beneficial effect in preventing the development of diseases.”
The study did not address the issue of whether hydroxychloroquine can prevent coronavirus infection if people take it before being exposed to a sick patient. This possibility is being investigated in other clinical studies involving health professionals, paramedics and other emergency workers.
At a Senate hearing on the supervision of the F.D.A. Democrats criticized the agency for its decision in March to grant hydroxychloroquine approval for an emergency over the manufacture of foreign medicines on Tuesday.
“I believe the FDA has given in to the pressure and issued a so-called” emergency permit “for the drug,” said Senator Ron Wyden of Oregon, the senior Democrat on the Senate Finance Committee, who sponsored the hearing. “This opened the door to tens of millions of pills, including some directly related to this hearing, which were manufactured in facilities in Pakistan and India that either failed F.D.A.’s inspection or were never inspected by F.D.A. at all.”
Sheila Kaplan contributed to the reporting.