(AP) — Researchers in England said they have the first evidence that a drug can improve survival from COVID-19.

Results released Tuesday show it reduced deaths by up to one third in severely ill hospitalized patients.

The drug, dexamethasone, is a cheap, widely available steroid that reduced deaths by 35 percent in patients who needed treatment with breathing machines and by 20 percent in those only needing supplemental oxygen.

The study was led by the University of Oxford. It involved thousands of patients randomly assigned to get the drug or just usual care.

It did not appear to help less ill patients.