US pharmaceutical giant Pfizer on Tuesday announced a deal to make its oral antiviral Covid-19 medication available more cheaply in poorer countries, if the promising pill passes trials and regulatory approval.

Pfizer, which also produces a Covid vaccine with German lab BioNTech, said it had signed an agreement to sub-licence production of its Paxlovid pill to generic drug manufacturers, without receiving royalties.

The deal with the global Medicines Patent Pool (MPP) would therefore make the candidate drug available at a lower cost in 95 low- and middle-income countries covering around 53 percent of the world's population.

It follows a similar deal for US rival Merck & Co last month. The drug is to be taken with the HIV medicine ritonavir.

Interim data from ongoing trials demonstrated an 89 percent reduction in the risk of Covid-19-related hospitalisation or death compared to a placebo, in non-hospitalised high-risk adults with Covid-19 within three days of symptom onset, said Pfizer. Similar results were seen within five days of symptom onset, it added.

Jacaranda News/AFP