The company hopes it will eventually be able to offer the pill, given in combination with an older antiviral called ritonavir, to people to take at home before they get sick enough to go to the hospital.
The results were so striking that the company halted the trial and is preparing to plead with the U.S. Food and Drug Administration for emergency approval of the drug.
“Today’s news is a real game-changer in the global effort to halt the devastation of this pandemic,” Pfizer CEO Albert Bourla said in a statement.
Pfizer released the results in a press release and did not provide scientists to discuss the data ahead of release. The data has not been peer reviewed or published. The company says it will share more details in a peer-reviewed paper and in its filing with the FDA.
On Friday’s CNN New Day, Bourla said the company plans to provide data to regulators as soon as possible, perhaps before Thanksgiving.
The company has tested the drug in adults with Covid-19 who are believed to be at high risk of developing serious illness. The volunteers were randomly given the pill combination or a placebo within three days or five days after their symptoms started.
The pill, called Paxlovid and also known by the experimental name PF-07321332, is known as a protease inhibitor. It is designed to prevent the virus from multiplying. Giving it along with ritonavir slows down its breakdown in the body, the company said.
Pfizer said 0.8% of patients who received the drug combination within three days were hospitalized within four weeks — three out of 389 patients — compared with 7% of patients who received placebos, or 27 out of 385. And seven of those taking placebos died, Pfizer said. No one who received the treatment died within a month.
Similar reductions in COVID-19-related hospitalization or death were observed in patients treated within five days of symptom onset; 1% of patients receiving PF-07321332 (with) ritonavir were hospitalized until and by day 28 post-randomization (6/607 hospitalized, with no deaths), compared to 6.7% of patients who received placebo,” the company said.
“It means that instead of ten going to the hospital, only one will go to the hospital and very few are likely to die,” Bourla told CNN.
It said 19% of patients who received the treatment experienced side effects, compared with 21% who received a placebo, but declined to disclose what those side effects were.
Bourla called the results “an amazing day for humanity,” noting that they came almost a year into the day the company announced the first results for its Covid-19 vaccine, which the company released on November 9, 2020.
Bourla said the pill could save millions of lives, but he still wanted to emphasize the importance of vaccination. But vaccines aren’t 100% effective, and not everyone will be vaccinated, Bourla said, which could lead to overcrowded hospitals and ICUs.
“Now we have a solution for that, and this is exactly where it fits,” Bourla said. “This is to treat those who have unfortunately contracted the disease.”
Currently, remdesivir, sold under the brand name Vekury, is the only antiviral drug approved by the FDA for the treatment of Covid-19. It is given by intravenous infusion, so it is not as easy to administer as a pill.
People can also be treated with monoclonal antibodies, which are injected or infused therapies that give the immune system a kick-start to help fight infection. They are not as easy to take as a pill and must be administered by a trained professional.
Merck is seeking emergency clearance from the FDA for molnupiravir, an antiviral capsule that people can take at home. It has been shown to reduce the risk of hospitalization or death by approximately 50%. On Thursday, UK drug regulators approved molnupiravir under the brand name Lagevrio.