June 4, 2020

Can hydroxychloroquine prevent the new coronavirus? A new study divides experts.

Daily Briefing

    The anti-malaria drug hydroxychloroquine did not prevent people who were exposed to the new coronavirus from becoming infected, according to new data from the first randomized controlled clinical trial examining whether the treatment could protect people from contracting the pathogen—but one expert has cautioned that the findings "are more provocative than definitive."

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    US Covid-19 cases surpass 1.8M, death toll tops 107K


    The data comes as U.S. officials as of Thursday morning had reported 1,861,200 cases of Covid-19, the disease caused by the new coronavirus—up from 1,841,400 cases as of Wednesday morning.

    As of Thursday morning, officials also had reported a total of 107,171 U.S. deaths linked to the new coronavirus—up from 106,195 deaths reported as of Wednesday morning.

    Trial suggests hydroxychloroquine does not prevent new coronavirus infections

    As the numbers of newly reported cases of Covid-19 and related deaths continue to rise throughout the United States, researchers and public health officials have been scrambling to develop vaccines to protect people against contracting the new coronavirus and treatments to treat Covid-19. One experimental treatment that researchers have been evaluating is the anti-malaria drug hydroxychloroquine, which President Trump has widely touted as a potential treatment for Covid-19. Trump last month said he was taking hydroxychloroquine in hopes of preventing infection from the new coronavirus.

    But health experts have noted that hydroxychloroquine hasn't been approved to treat or prevent Covid-19. In addition, some research has found it can cause patients to experience serious heart rhythm problems.

    Now, the newly released data from American and Canadian researchers, which was published Wednesday in the New England Journal of Medicine, suggests hydroxychloroquine is not effective at preventing infections from the new coronavirus.

    The researchers conducted a randomized controlled trial involving 821 participants. Sixty-six percent of the participants were young and healthy health care workers. The remaining participants were people who had been exposed to the new coronavirus at home through their spouses, partners, or parents. All the participants, who ranged in age from 33 to 50, either had high-risk or moderate-risk exposure to a person who tested positive for the new coronavirus and developed Covid-19.

    According to the researchers, high-risk exposure occurs when people without a mask or face shield are less than six feet away from a person with a confirmed infection of the new coronavirus for more than 10 minutes, while moderate-risk exposure occurs when people wear a face mask but no shield and are otherwise exposed in the same manner. Among the trial's participants, 88% had high-risk exposures to the new coronavirus, while the rest had moderate-risk exposures.

    The researchers treated 414 participants with hydroxychloroquine and gave 407 participants a placebo to evaluate the drug's potential to prevent the new coronavirus. Participants received the treatments via the mail. The researchers noted that none of the study participants had tested positive for the new coronavirus or were experiencing symptoms of Covid-19 at the start of the study, and none had underlying health conditions that would have put them at risk when using hydroxychloroquine.

    The researchers then followed up with the participants throughout the following 14 days to determine whether the participants had developed a laboratory-confirmed case of new coronavirus infection or symptoms associated with Covid-19. Participants reported any Covid-19 symptoms or confirmed cases of infection to the researchers online, and the researchers did not conduct in-person evaluations of the participants. According to the researchers, not all participants could be tested for the new coronavirus because of a shortage of testing kits at the time.

    They found no statistically significant difference in infection rates between the group of participants who took hydroxychloroquine and those who took a placebo. Among the 414 participants who took hydroxychloroquine, 11.8%, or 49, tested positive for the new coronavirus or reported symptoms associated with Covid-19, while 14.3%, or 58, of the 407 participants who took a placebo tested positive for the new coronavirus or reported symptoms associated with Covid-19.

    The researchers also found hydroxychloroquine did not appear to affect the severity of Covid-19 symptoms that participants reported. According to the researchers, participants who took hydroxychloroquine reported side effects such as nausea more often than patients who took the placebo, but none of the patients reported heart rhythm problems or any severe adverse reactions. The researchers found 40.1% of participants who took hydroxychloroquine reported side effects, compared with 16.8% of participants who took a placebo.

    Some say results show hydroxychloroquine doesn't prevent infection, but others aren't so sure

    David Boulware from the University of Minnesota, who was the study's lead author, said, "The take-home message for the general public is that if you're exposed to someone infected with the new coronavirus, hydroxychloroquine is not an effective post-exposure preventive therapy."

    William Schaffner, an infectious disease specialist at Vanderbilt University, said although hydroxychloroquine prevented the new coronavirus from infecting cells in some laboratory studies, "that did not translate into a beneficial effect in preventing the development of illness" in the clinical trial.

    But Myron Cohen of the University of North Carolina at Chapel Hill in an editorial accompanying the new data wrote that the trial's results "are more provocative than definitive." Cohen wrote, for example, that there's a possibility that hydroxychloroquine might prevent new coronavirus infections if taken sooner or in a different manner. In addition, Cohen noted that the trial had "many limitations" acknowledged by the researchers that could affect the results, including a lack of adequate testing for the new coronavirus among participants and participants' self-reporting,.

    Ultimately, Cohen wrote, "[t]he potential prevention benefits of hydroxychloroquine remain to be determined."

    WHO resumes hydroxychloroquine trial

    Separately, the World Health Organization (WHO) on Wednesday announced it will resume its clinical trial examining whether hydroxychloroquine can effectively treat Covid-19, after the organization last month paused enrollment in the trial because of concerns that the drug increased the risks of death and heart problems among patients with the disease.

    The announcement came after researchers behind a large study that examined the risks and benefits of using hydroxychloroquine as a potential treatment for Covid-19 this week posted corrections to the study amid concerns over inconsistencies in some of the data used for the research.

    Tedros Adhanom Ghebreyesus, WHO's director-general, said WHO's experts have recommended that the agency resume its trial.

    Soumya Swaminathan, WHO's deputy director, said, "We owe it to patients to have a definitive answer on whether or not a drug works." She continued, "As of now, there is no evidence that any drug actually reduces the mortality in patients who have Covid-19, and in fact it is an urgent priority for all of us to do the needed studies, to do the randomized clinical trials in order to get that evidence as quickly as possible" (Grady, New York Times, 6/3; Herper, STAT News, 6/3; Marchione, Associated Press, 6/3; Hopkins, Wall Street Journal, 6/3; McGinley/Cha, Washington Post, 6/3; Boulware at al., New England Journal of Medicine, 6/3; Cohen, New England Journal of Medicine, 6/3; Joseph, STAT News, 6/3; Shields/Farge, Reuters, 6/3; New York Times, 6/4).

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