London, Jun 16 (IANS): Cheap and commonly available corticosteroid Dexamethasone, used to treat arthritis, immune system disorders, and allergic reactions, among others, may be a "magic bullet" in the war against coronavirus, helping to save seriously-ill Covid patients, British researchers say.

British experts say the low-dose steroid -- which costs around five pounds -- is a major breakthrough in the fight against the deadly virus, cutting the risk of death by a third for patients on ventilators, the BBC reported.

For those on oxygen, it cuts deaths by a fifth.

Dexamethasone is part of the world's biggest trial testing existing treatments to see if they also work for coronavirus.

The results from the 'Recovery' trial, led by a team from Oxford University, suggest the steroid can prevent death in one in eight ventilated coronavirus patients and one in 25 on breathing support, British media reported.

Dexamethasone, which is given either via an injection or as a once-a-day tablet, becomes the first drug proven to treat the incurable viral disease.

In the trial, around 2,000 hospital patients were given dexamethasone and were compared with more than 4,000 who did not receive the drug.

For patients on ventilators, it cut the risk of death from 40 per cent to 28 per cent For patients needing oxygen, it cut the risk of death from 25 per cent to 20 per cent.

Chief investigator Prof Peter Horby said: "This is the only drug so far that has been shown to reduce mortality - and it reduces it significantly. It's a major breakthrough," the BBC report said.

Lead researcher Prof Martin Landray held the findings suggest that for every eight patients treated on ventilators, one life could be saved, and for those patients treated with oxygen, one life for approximately every 20-25 treated with the drug could be saved.

"There is a clear, clear benefit. The treatment is up to 10 days of dexamethasone and it costs about 5 pounds per patient. So essentially it costs 35 pounds to save a life. This is a drug that is globally available."

Prof Landray said that when appropriate, hospital patients should now be given it without delay, but cautioned people not to go out and buy it to take at home.

Dexamethasone does not appear to help people with milder symptoms of coronavirus - those who don't need help with their breathing.

The Recovery Trial has been running since March. It included the malaria drug hydroxychloroquine which has subsequently been ditched amid concerns that it increases fatalities and heart problems.

Dexamethasone was first discovered in 1957 and is commonly prescribed to patients with allergic disorders, skin conditions, ulcerative colitis, arthritis and some types of cancer.

Researchers claim that that if the drug had been used to treat patients in the UK from the start of the coronavirus pandemic, up to 5,000 lives could have been saved.

Because it is cheap, it could also be of huge benefit in poorer countries struggling with high numbers of Covid-19 patients.