Scientists from the University of Oxford were the first to find a treatment for the Coronavirus.
Using dexamethasone to treat Covid-19 patients could have saved 650,000 lives around the world, a study suggests.
This includes 12,000 British lives.
Oxford University's large clinical trial, known as Recovery, found that dexamethasone, a cheap and widely available steroid, could reduce deaths from Covid-19 significantly.
The researchers found that the drug cut the risk of death by a third for patients on ventilators.
For those on oxygen, it cut deaths by almost a fifth.
The scientists reported their findings last year in June.
Now, the Oxford experts have analysed how many lives have potentially been saved as a result of the treatment between July and December 2020.
The new study, published in the journal Nature Communications, concluded that the use of the treatment had saved 12,000 lives in the UK.
But this could be up to 27,000 lives, the authors found.
Around the world the estimate is 650,000 lives – but this could be up to 1.4 million.
One of the chief investigators for the Recovery trial, Oxford Professor Peter Horby, said: “Dexamethasone is a globally accessible and highly cost effective treatment for hospitalised Covid-19.
“Clinical trials can be done during health emergencies, change practices and save lives.”
Commenting on the news, Professor Stephen Powis, national medical director for the NHS in England, said: “This study shows the NHS’ ability to effectively put research into practice and from vaccinating the first patients outside of clinical trials to helping get dexamethasone into frontline care, the NHS has led the way in improving treatment for patients with Covid, saving thousands of lives.”