An inexpensive antidepressant used to treat obsessive-compulsive disorder, also helps lower the likelihood of high-risk COVID-19 patients requiring hospitalization or prolonged medical observation, a large clinical trial published in The Lancet suggests.

The drug, fluvoxamine, has been prescribed to treat OCD for nearly 30 years, but researchers began looking into it more carefully at the onset of the pandemic, based on its ability to reduce inflammation, with hopes it could subdue the body's intense response to the infection.

The results of the study, which were published Wednesday by a group of researchers in Canada, the US, and Brazil, could mean a new set of guidelines for use of the drug both in the US and abroad. And at only about $US4 ($AU5) for a 10-day course, the drug could be a particularly helpful remedy in less wealthy countries.

Dr. David Boulware, an infectious disease scientist at the University of Minnesota, told The New York Times fluvoxamine is "not a shiny new, expensive drug."

"The nice thing about this is it has a known safety profile," he told the outlet.

The study, which was published in The Lancet Global Health, followed nearly 1,500 COVID patients in Brazil who were given either fluvoxamine or a placebo. Researchers found that the drug reduced hospitalization or longterm medical observation rates by one-third.

Outside scientists noted that questions remain regarding the correct dosage, as some patients reportedly had difficulties tolerating the drug and ceased taking it, The Times reported.

But among patients who finished their regiment, the drug reduced the need for hospitalization at an even more significant rate: by two-thirds. The drug also cut the odds of COVID-related death.

Of the participants, 12 who were given a placebo died, while just one taking fluvoxamine did.

It is still unclear how the drug might work among those who are vaccinated, as the majority of study patients were unvaccinated. And running large COVID trials has proven difficult, particularly in the US, where most high-risk patients have already received the vaccine and the remaining unvaccinated could be less enthusiastic to join a study, The Times reported.

But because fluvoxamine is already on the market, doctors can prescribe the drug "off label" for COVID-19, according to the outlet, though it has yet to develop the cult following that other, less-researched drugs like hydroxychloroquine and ivermectin garnered.

This article was originally published by Business Insider.

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