A Covid tablet has been found to cut the number of hospitalisations and deaths by half among recently infected people in results from a clinical trial.
If approved, it would become the first simple oral medicine found to be effective against coronavirus in the fight against the pandemic.
Merck and Ridgeback Biotherapeutics made the antiviral pill designed to introduce errors into the genetic code of the virus.
The US firm plans to get emergency use authorisation for the pill in the states as soon as possible and to submit applications to regulatory agencies worldwide.
Merck CEO Robert Davis said: “This is going to change the dialogue around how to manage Covid-19.”
Clinical trial results revealed on Friday the experimental medicine, named molnupiravir, could reduce hospitalisations and deaths by 50 per cent for those at risk of severe disease.
Dean Li, the vice-president of Merck research, said: “It exceeded what I thought the drug might be able to do in this clinical trial.
“When you see a 50% reduction in hospitalisation or death that’s a substantial clinical impact.”
Rivals - including Pfizer Inc and Swiss pharmaceutical Roche Holding AG - are determined to develop an easy-to-administer antiviral pill for Covid.
Of 775 patients, Merck’s study found 7.3 per cent of those given molnupiravir were either hospitalised or had died by 29 days after treatment.
This was compared with 14.1 per cent of placebo patients.
There were no deaths in the molnupiravir group but there were eight deaths of placebo patients.
“Antiviral treatments that can be taken at home to keep people with Covid-19 out of the hospital are critically needed,” Wendy Holman, Ridgeback’s CEO, said in a statement.
Scientists welcomed the potential new treatment to help prevent serious illness from the virus which has swept the globe.
Professor Penny Ward, visiting professor in pharmaceutical medicine at King’s College London, said: “The availability of a well-tolerated, effective oral antiviral will be particularly useful in supplementing vaccination as a means to reduce the proportion of patients needing hospital care,”
Patients from all over the world took part in the trial where molnupiravir was taken every 12 hours for five days.
It involved people who had laboratory-confirmed mild-to-moderate Covid and who had symptoms for no more than five days.