Pfizer’s pill is the second oral drug for COVID-19 to be proven strongly effective in large, placebo-controlled clinical trials after Merck’s molnupiravir, which early in November was authorized by regulators in the U.K.
Both treatments, which work in different ways to prevent the coronavirus from replicating itself, were tested in generally similar groups: people with mild or moderate COVID-19 who were likelier to experience severe symptoms due to their health.
In the case of Pfizer’s drug, treatment within three days of symptoms beginning reduced the risk of hospitalization or death by 89% versus placebo, and by 85% if given within five days of symptoms. Six of the 607 people given Paxlovid in the study were hospitalized, compared to 41 of the 612 who received placebo. No one in the treatment group died, while 10 people in the placebo arm did.
While comparing across trials can be misleading, Merck’s study of molnupiravir also showed a significant 50% reduction in the risk of hospitalization and death.
Detailed data are not yet available from either Pfizer or Merck, both of which announced their preliminary trial results via press release.
But the dramatic benefit has boosted hopes of a convenient and easy-to-make treatment for the many people who are still at high risk of severe COVID-19. Unlike monoclonal antibodies, which are highly effective but must be given intravenously, Paxlovid and molnupiravir could be taken at home.
Merck and its partner Ridgeback Biotherapeutics applied for emergency authorization from the FDA in mid-October, and an FDA advisory committee is set to review the drug on Nov. 30.
Pfizer is following with a quick application of its own. The drugmaker began submitting non-clinical data to the FDA last month and has now filed its clinical results.
In addition to the U.S., Pfizer is also applying for authorization in the U.K., Australia, New Zealand and South Korea, and plans to file further submissions in other countries as well.
As with its vaccine, Pfizer’s pill is likely to be in high demand. The company expects to be able to produce 50 million treatment courses next year and, on Tuesday, announced a deal with The Medicines Patent Pool to license the drug to generic manufacturers around the world.
The Washington Post, meanwhile, reported the Biden administration is close to reaching a supply deal with Pfizer for 10 million courses. Paxlovid is administered as two tablets taken twice daily for five days. The drug is coadministered with ritonavir, an old HIV drug that slows how quickly Paxlovid is metabolized in the body.
The U.S. has already spent several billion dollars to secure supplies of Merck’s molnupiravir, which will be sold as Lagevrio.