The first study to investigate the effect of taking the antimalarial drug hydroxychloroquine shortly after the onset of symptoms has found no significant reduction in symptoms.

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A new study concludes that hydroxychloroquine does not improve symptoms even if taken early.

All data and statistics are based on publicly available data at the time of publication. Some information may be out of date.

There are currently no proven treatments for non-hospitalized patients with mild to moderate COVID-19, the disease caused by the coronavirus SARS-CoV-2.

Previous studies have shown that the antimalarial hydroxychloroquine provides no clinical benefit for patients in the hospital. However, researchers still hoped that it might be effective if a person takes it early in the course of the disease.

Researchers led by the University of Minnesota in Minneapolis hypothesized that if patients took the drug shortly after the onset of symptoms, it could reduce the severity and duration of COVID-19 and prevent hospitalization.

To test their hypothesis, they enrolled 491 individuals in the United States and Canada, who had been experiencing symptoms for 4 days or less.

All the participants had tested positive for COVID-19, had been in close contact with someone who had tested positive within the past 14 days, or were healthcare workers who an infectious disease specialist strongly suspected had COVID-19.

The researchers randomly assigned the volunteers to receive unlabelled tablets via courier that contained either 200 milligrams (mg) of hydroxychloroquine or a placebo.

The researchers asked the participants to take four tablets initially, then three tablets 6–8 hours later, then three tablets once each day for 4 more days.

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The participants reported the severity of their symptoms online for 14 days.

Among the 423 participants who provided all the necessary data, the researchers found no significant difference between the severity of symptoms experienced by those who took hydroxychloroquine and those who took the placebo.

After 14 days, 24% of those who took the drug still had symptoms compared with 30% of those who took the placebo, but this result was not statistically significant.

There was also no significant difference in rates of hospitalization between the two groups.

However, there was a significant difference in adverse effects. The results showed that 43% of those who took hydroxychloroquine experienced adverse events compared with 22% of those who took the placebo.

The researchers published their results in the Annals of Internal Medicine. The authors conclude:

“In conclusion, finding effective therapies against COVID-19 remains critical. Effective treatment of early, outpatient COVID-19 could decrease hospitalizations and, ultimately, morbidity and mortality. Hydroxychloroquine did not substantially reduce symptom severity or prevalence over time in nonhospitalized persons with early COVID-19.”

The authors note that the poor availability of community testing for SARS-CoV-2 in the U.S. early in the pandemic presented a significant challenge for their research.

As a result, only 34% of participants had a laboratory-confirmed infection. The remainder reported coming into close contact with someone with a confirmed infection.

In addition, they write that the majority of their subjects were relatively young and may, therefore, be unrepresentative of the broader population.

“It is possible that hydroxychloroquine is more effective in populations at higher risk for complications, such as older persons in long-term care facilities,” they write.

However, they caution that these people will also be at higher risk of adverse drug effects and interactions with other medications.

In an accompanying editorial, Dr. Neil Schluger of New York Medical College, NY, says the story of hydroxychloroquine should serve as a cautionary tale about how experts evaluate and promulgate treatments during health emergencies. He writes:

“Early in the COVID-19 pandemic, hydroxychloroquine quickly came to be widely used on the basis of very thin evidence […] Professional societies, public health agencies, and many politicians with no expertise in science or medicine allowed, endorsed, or promoted the use of hydroxychloroquine.”

He notes that two large observational studies, published in the New England Journal of Medicine and JAMA, found no association between administration of hydroxychloroquine and the rate of death or respiratory failure in hospitalized patients.

This supports the National Institutes of Health recommendation that the drug should only be used in clinical trials, not routine care.

Schluger writes that preliminary results from two large randomized controlled trials in the United Kingdom and the U.S. — as yet unpublished — suggest that the drug is not an effective treatment for patients hospitalized with COVID-19.

Medical News Today have published a roundup of scientific evidence relating to hydroxychloroquine and COVID-19, including its possible adverse effects.

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