The United Kingdom has launched a trial to test a COVID-19 treatment that can be taken in pill form at home, potentially reducing the risk of severe symptoms and hospitalizations.

The UK-wide PANORAMIC clinical trial, led by the University of Oxford, is assessing the antiviral pill Molnupiravir in 10,000 people who register for the study and go on to test positive for COVID-19.

Eligible candidates include those aged 50 years and older, and 18 to 49 year olds with underlying health conditions, or who have been unwell with COVID-19 for less than five days.

The government announced that, from Dec 16, Molnupiravir will also be made available outside the study, to people at the highest risk of severe illness, including those who are immunocompromised, cancer patients, and those with Down's Syndrome.

Previous trials have shown that Molnupiravir can reduce the risk of hospitalization or death in adults with mild to moderate COVID-19 by 30 percent.

Health Secretary Sajid Javid called the national study a "historic milestone in our battle against the virus", paving the way for the first medicines that people will be able to take "in the comfort of their own homes to protect themselves".

Chris Butler, a primary care professor at University of Oxford and chief investigator on the trial, said participants will have the drug sent directly to their homes.

"It's vital that as many people as possible who are at higher risk from complications of COVID-19 join the trial, so we can rapidly learn if exciting new treatments really do help people get better quicker and reduce pressures on the National Health Service," Butler said.

The UK's deputy chief medical officer, Jonathan Van-Tam, said that antiviral drugs could provide a "vital intervention for years to come". The UK has achieved high vaccination coverage, though the rate of infections is still high, averaging almost 48,000 per day this week, and there are concerns that existing vaccines may be less effective against new variants, including Omicron.

Molnupiravir, an experimental antiviral initially developed to treat influenza, performed well in clinical trials for the treatment of COVID-19 this fall, after which the UK drug regulator approved the drug for use in November.

The UK ordered 480,000 courses of Molnupiravir from pharmaceutical company Merck Sharp and Dohme in October, in preparation for a spike in COVID-19 infections this winter.

The UK also ordered 250,000 courses of Ritonavir, another drug that can be taken in pill form. Ritonavir is most commonly used to treat HIV/AIDS, and the antiviral has shown promise in reducing severe illness and hospitalization from COVID-19 in trials run by Pfizer.

The PANORAMIC program will next launch a nationwide trial for Ronapreve, a novel monoclonal antibody treatment for COVID-19, with more drug trials to follow under the program.