Treating COVID-19 patients at home with a commonly-used inhaled asthma drug called budesonide can speed up their recovery, according to UK trial results on Monday which doctors said could change the way the disease is treated around the world.

Researchers behind the trial – known as PRINCIPLE – said the findings were only an interim analysis at this stage, but could soon lead doctors to prescribe budesonide inhalers to patients infected with Covid-19 but not sick enough to be hospitalised.

“For the first time we have high-quality evidence of an effective treatment that can be rolled out across the community for people who are at most risk of developing more severe illness from Covid-19,” said Richard Hobbs, a professor at Britain’s Oxford University who co-led the trial.

He noted that unlike other proven Covid-19 treatments, such as the steroid dexamethasone, budesonide is effective in early stages of Covid-19 and can be used at home. “This is a significant milestone for this pandemic,” he said.

The PRINCIPLE results add to recent evidence from a smaller UK study, which found in February that budesonide reduced recovery time and the need for hospitalisation among Covid-19 patients given it within a week of first symptoms.

Budesonide is a safe, relatively cheap and readily available corticosteroid drug used around the world in inhalers to treat asthma and chronic obstructive pulmonary disease (COPD).

“Medical practitioners around the world caring for people with Covid-19 in the community may wish to consider this evidence when making treatment decisions,” said Chris Butler, a family doctor and Oxford professor who co-led the PRINCIPLE study. “It should help people with Covid-19 recover quicker.”

The study involved 961 patients who were randomly assigned to receive inhaled budesonide and compared to 1,819 patients assigned to the usual standard of care. Some 751 people in the budesonide group and 1,028 in the usual care group were SARS-CoV-2 positive and included in the interim analysis.

Doctors asked the budesonide patients to take two puffs on the inhaler, twice a day for a fortnight – giving an inhaled dose of 800 micrograms twice a day for 14 days. All patients were either age 65 plus, or aged over 50 with an underlying health condition that put them at more risk of serious COVID-19.

Interim results, published before peer-review on the medRxiv server, showed that 32 per cent of those on inhaled budesonide, compared with 22 per cent in the usual care group, recovered within the first 14 days and remained well until at least 28 days of follow-up.

Butler’s team said a full analysis with detailed results on time to recovery and hospitalisations would be published when all remaining trial patients have completed follow-up.