The US National Institutes of Health (NIH) on Friday said that data from its trial of Gilead Sciences Inc’s remdesivir show that the drug offers the most benefit for COVID-19 patients who need extra oxygen but do not require mechanical ventilation.

The peer-reviewed data was published in the New England Journal of Medicine.

The trial, for which final results are still trickling in, showed that recovery time for patients given remdesivir was shortened by four days, or 31 per cent, compared to placebo patients. The biggest benefit was seen in patients who were sick enough to need supplemental oxygen, but were not on a ventilator.

The data detailed in the journal is similar to early results that the NIH released last month from the study, which began in February with 1,063 participants in 10 countries.

Researchers now calculate that after follow-up, 7.0 per cent of patients given remdesivir will have died, compared with 12 per cent in the placebo group, but they said the difference in the death rate was not significant.

“Our findings highlight the need to identify COVID-19 cases and start antiviral treatment before the pulmonary disease progresses to require mechanical ventilation,” the researchers wrote.

They noted that “given high mortality despite the use of remdesivir,” it is likely that the antiviral drug would be more effective in combination with other treatments for COVID-19, the respiratory illness caused by the novel coronavirus.

Gilead said it expects results from its own study of remdesivir in patients with moderate COVID-19 at the end of this month.

“We look forward to the initiation of combination studies of remdesivir to understand whether the addition of other drugs may enhance patient outcomes,” Gilead Chief Medical Officer Merdad Parsey said in a statement.

The Food and Drug Administration authorised emergency use of remdesivir on May 01, and Gilead has been supplying the drug to hospitals as part of a pledge to donate 1.5 million vials - or enough for at least 140,000 patients.