LONDON — Scientists at the University of Oxford said on Tuesday that they had identified what they called the first drug proven to reduce coronavirus-related deaths, after a 6,000-patient trial in Britain showed that a low-cost steroid prevented the deaths of some hospitalized patients.
The steroid, dexamethasone, a well-known anti-inflammatory drug, appeared to help patients with severe cases of the virus: It reduced deaths by a third in patients receiving ventilation, and by a fifth in patients receiving standard oxygen treatment, the scientists said. They found no benefit from the drug for patients who did not need respiratory support.
Medical experts said that further study was needed to determine precisely how the steroid helped patients but that it appeared to reduce damage to lung tissue. Experts said it appeared that the steroid tamped down the overactive inflammatory response to the virus in some patients, known as a cytokine storm, rather than inhibiting the virus itself.
The trial results have not been published in a peer-reviewed journal, but the findings will be welcomed as scientists around the world race to find ways to treat a virus that has killed nearly 440,000 people and infected more than eight million.
Matt Hancock, Britain’s health secretary, said doctors in the country’s National Health Service would begin using the steroid as the standard treatment for hospitalized coronavirus patients on Tuesday afternoon.
The government started stockpiling dexamethasone several months ago based on signs that it could help patients, Mr. Hancock said, and now has 200,000 doses on hand.
“Dexamethasone is the first drug to be shown to improve survival in Covid-19,” one of the chief investigators for the trial, Peter Horby, who is a professor of emerging infectious diseases at the University of Oxford, said in a statement. “The survival benefit is clear and large in those patients who are sick enough to require oxygen treatment.”
Professor Horby said that dexamethasone should now become the “standard of care in these patients,” noting that it was inexpensive, widely available and could be used immediately.
Some doctors urged caution about the results. With scientists rushing to identify treatments for the virus as the outbreak spread around the world, some high-profile findings have had to be retracted or walked back in recent months.
But outside experts said the early results were promising.
“This outcome for patients suffering from severe Covid-19 in need of respiratory assistance is of tremendous importance,” Dr. Stephen Griffin, an associate professor in virology at the University of Leeds, said in comments to Britain’s Science Media Centre. “The low cost and broad availability of this drug means that there is potential for considerable clinical impact by including it as part of standard treatment.”
Dr. Griffin said further research would be important in establishing how the steroid might be combined with virus-targeted therapies like remdesivir.
As part of the trial, about 2,100 patients were given low doses of dexamethasone, orally or intravenously, once a day. Their outcomes were compared to another 4,300 patients who received the usual care.
Based on their findings, the Oxford scientists said, the drug would prevent one death for every eight ventilated patients.