Pfizer Inc says 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 has 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.

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 October 11.

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