Dexamethasone, a cheap and widely used steroid, has become the first drug shown to be able to save lives among Covid-19 patients in what scientists hailed as a “major breakthrough”.

Results of trials announced on Tuesday showed dexamethasone, which is used to reduce inflammation in other diseases, reduced death rates by around a third among the most severely ill Covid-19 patients admitted to hospital.

The results suggest the drug should immediately become standard care in patients with severe cases of the pandemic disease, said the researchers who led the trials.