NEW YORK (BLOOMBERG) - A common antidepressant appears to reduce the risk of death in patients admitted to hospital with severe Covid-19, according to a study published in the Jama Network Open journal.

About 9.8 per cent of the 470 Covid-19 patients in the study who were taking fluoxetine, also sold under the brand name Prozac, died.

That is compared with more than 13 per cent of patients with similar characteristics not receiving any antidepressants.

A recent trial in Brazil showed that fluvoxamine, another antidepressant, may reduce the risk that a patient with Covid-19 ends up in hospital.

The antidepressant was chosen to be studied as a potential treatment for Covid-19 because of its anti-inflammatory properties.

It is also cheaper than Merck's new antiviral pill for Covid-19. The pharmaceutical giant is known as MSD outside the United States and Canada.

"Although further studies are needed, this raises the prospect of repurposing these antidepressants as treatments for Covid-19," said Professor Allan Young, director of the Centre for Affective Disorders, Institute of Psychiatry, Psychology & Neuroscience, at King's College London, who reviewed the study.

Fluoxetine and fluvoxamine have been safely used for almost 30 years as treatments for mental health conditions such as depression and obsessive-compulsive disorders.

They are part of the most commonly prescribed type of antidepressants called selective serotonin reuptake inhibitors, or SSRIs, which ease symptoms by increasing serotonin levels in the brain.

Another reviewer of the study said that it is observational and too small to give evidence of cause and effect.

Other limitations include the fact that records on previous health conditions were not available for all patients, said Emeritus Professor of Applied Statistics Kevin McConway at The Open University.