Pfizer Inc said on Tuesday it is seeking US authorisation of its experimental antiviral Covid-19 pill that cut the chance of hospitalisation or death for adults at risk of severe disease by 89 per cent in a clinical trial.

Pfizer said it completed submission of its application for emergency use authorisation (EUA) of the drug, Paxlovid, with the US Food and Drug Administration, including data from the drugmaker's clinical trial.

The oral drug could be a promising new weapon in the fight against the pandemic, as it can be taken as an early at-home treatment to help prevent Covid-19 hospitalisations and deaths. It could also become a important tool in countries and areas with limited access to vaccines or low vaccination rates.

It is not immediately clear when US regulators will rule on Pfizer's application. Merck & Co and Ridgeback Biotherapeutics, which are developing a competing pill, molnupiravir, completed their EUA submission on Oct 11.

A panel of outside advisers to the FDA will meet to consider that application on Nov 30. It is expected to be available this year.

“We are moving as quickly as possible in our effort to get this potential treatment into the hands of patients, and we look forward to working with the US FDA on its review of our application, along with other regulatory agencies around the world,” Pfizer Chief Executive Albert Bourla said in a news release.

A Pfizer spokesperson said that the data the company is submitting came from testing the medicine on unvaccinated, high-risk participants.

The FDA will make the final decision on who the drug will be indicated for and how it can be used.

The New York-based drugmaker said it has begun the process of seeking authorisation of the treatment in several countries including the United Kingdom, Australia, New Zealand and South Korea, and plans further international submissions.

Pfizer has said it expects to manufacture 180,000 treatment courses by the end of next month and at least 50 million courses by the end of 2022.

The company earlier on Tuesday said it will allow generic manufacturers to supply its Covid-19 pill to 95 low- and middle-income countries through a licencing agreement with international public health group Medicines Patent Pool (MPP).