An experimental pill developed by Pfizer was found to reduce hospitalizations and deaths from Covid-19 by almost 90% when given within three days of symptom onset—suggesting the pill could be a major boon in the fight against the coronavirus.
Details on the pill
The pill, which is called Paxlovid, is a protease inhibitor that blocks a key enzyme that the coronavirus needs to replicate. The drug is intended to be taken alongside ritonavir, a drug currently used in combination treatments for HIV infection. According to Pfizer, ritonavir slows the breakdown of Paxlovid and so extends the duration of its effectiveness in the body.
In a trial of more than 750 people, Paxlovid was found to reduce the risk of hospitalization and death from Covid-19 by 89% when given within three days of symptoms starting.
In particular, in the group of trial participants who received a placebo, there were 10 deaths from Covid-19, while no one in the Paxlovid group died during the trial.
According to Pfizer, Paxlovid was also found to be active against multiple variants of the coronavirus, including the delta variant, in lab testing.
'Beyond our wildest dreams'
Paxlovid is the second oral antiviral drug to show strong evidence of efficacy against Covid-19. On Thursday, the United Kingdom became the first country to approve a separate antiviral, molnupiravir, which was developed by Merck and Ridgeback Biotherapeutics and reduced hospitalizations and deaths by about 50% in a clinical trial.
Nahid Bhadelia, founding director of the Center for Emerging Infectious Diseases Policy & Research at Boston University, said that oral antiviral pills are "incredibly important" because current treatments for Covid-19, including monoclonal antibodies, must be given intravenously.
"With an oral antiviral, patients have more time and greater access to a treatment that will keep them out of the hospital," Bhadelia said. "But the promise of oral antivirals will only be recognized if they're available at your local pharmacy, and you can afford it, and you can get the test that tells you that you're positive for Covid, so you can actually take advantage of this drug. So, the promise is there, but the rest of the pieces need to come together."
Pfizer CEO Albert Bourla in a statement said the results of the Paxlovid study marked "a real game-changer in the global efforts to halt the devastation of this pandemic."
"The results are really beyond our wildest dreams," said Annaliesa Anderson, an executive at Pfizer who led Paxlovid's development. She added that she's hopeful the drug "can have a big impact on helping all our lives go back to normal again and seeing the end of the pandemic."
"It's stunning data," said Mikael Dolsten, Pfizer's chief scientific officer. "I feel very optimistic on a day like this. For everyone living in this pandemic, a new light of hope has turned on."
Pfizer said it will submit its findings to FDA for emergency use authorization "as soon as possible."
Paxlovid could become available within the next few months, the New York Times reports, but supplies could be limited at first, as the drug is primarily geared toward high-risk patients.
Angie Rasmussen, a vaccine researcher at the Vaccine and Infectious Disease Organization-International Vaccine Centre in Canada, expressed concerns about ensuring Paxlovid is available equitably worldwide.
"Without question, having new antivirals to add to the mix is a 'game-changer,' but the utility in the global efforts to halt the devastation of this pandemic remains to be seen," Rasmussen said.
According to Dolsten, "It is Pfizer's ambition to make this medicine accessible to as many patients as possible on the globe. We'll find the best way to do that." (Robbins, New York Times, 11/5; Falconer, Axios, 11/5; Herper, STAT News, 11/5; Hopkins, Wall Street Journal, 11/5; Weintraub, USA Today, 11/5)