What is dexamethasone? The coronavirus treatment proven to reduce the risk of death

Scientists have made the "biggest breakthrough yet" in the fight against coronavirus.

A trial has found the drug dexamethasone reduces the risk of death in coronavirus patients who have breathing difficulties.

Boris Johnson praised the team of scientists and hailed the findings during the daily government briefing. He added that dexamethasone "can now be made available across the NHS" as a coronavirus treatment.

Here's all you need to know.

What is dexamethasone?

Dexamethasone is a steroid drug. It's an inexpensive drug that is widely available.

What are the findings?

Peter Horby, leader of the RECOVERY trial, explained the findings in the daily briefing where he outlined the significant impact the drug had on the patients.

"In ventilated patients with Covid-19 the drug dexamethasone - with 10 days of treatment via tablet or injection - reduces the risk of death by about 35%. In patients on the ward who require oxygen and have Covid, it reduces the risk of death by 20%. That covers about 75% of patients in hospital who will receive a mortality benefit from using this drug," he said.

However, Mr Horby added that the treatment didn't benefit patients who have Covid-19 but don't require oxygen.

"It's not a drug you would use in the community or in outpatients or in patients on the ward who didn't have breathing difficulties. But in patients with breathing difficulties who require oxygen or ventilation it really is showing quite a signifiant effect," he said.

When will the treatment be made available for NHS patients?

Sir Patrick Vallance said the Chief Medical Officer "will be issuing guidance shortly."

"The idea is to get on with this and certainly make this as available as possible every where in the world," he added.