A low-cost synthetic steroid has been found to reduce COVID-19 deaths by up to a third in what is being described as a “groundbreaking development” in the fight against the virus.

The British government announced on Tuesday that dexamethasone is to be used on COVID-19 patients “from this afternoon.”

Dexamethasone was one of several drugs tested by the UK’s Recovery trial  between March and June.

More than 2,100 COVID-19 patients were treated with a low-dose of the steroid once per day for 10 days and results were compared with 4,321 patients receiving only the usual care.

Researchers found that dexamethasone reduced death by one-third in ventilated patients — those with severe respiratory complications due to the novel coronavirus — and by one fifth in other patients receiving oxygen only.

There was no benefit among those patients who did not require respiratory support and the trial did not involve any patients outside a hospital setting.

Peter Hornby, a professor of Emerging Infectious Diseases at the University of Oxford and one of the Chief Investigators for the trial, said that dexamethasone “is the first drug to be shown to improve survival in COVID-19,” and that it should therefore “become standard care” in patients requiring oxygen treatment.