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Pfizer says new trial confirms high efficacy of its COVID antiviral pills

Data released on Pfizer's COVID pill
Pfizer CEO: COVID antiviral pill reduces hospitalization rates up to 89% in high-risk adults 06:11

Pfizer announced new results on Tuesday from studies testing its five-day course of COVID antiviral pills, confirming Paxlovid cut the risk of hospitalization or death in a trial for patients at high-risk of severe COVID-19 by 89% when treated within the first three days of their symptoms. 

Pfizer also announced an interim analysis of data from another trial that found a 70% reduction in the risk of hospitalization and no deaths compared to placebo, in a study that also included unvaccinated adults who did not have underlying conditions putting them at high-risk of severe COVID-19. 

The company says early results from its lab tests shows its antiviral will likely remain effective against all variants of concern, including Omicron.  

"Emerging variants of concern, like Omicron, have exacerbated the need for accessible treatment options for those who contract the virus, and we are confident that, if authorized or approved, this potential treatment could be a critical tool to help quell the pandemic," Pfizer's CEO Albert Bourla said in a statement. 

Bourla called the treatment a "game changer" Tuesday on "CBS Mornings" and said that Paxlovid could be available this month if the FDA provides emergency authorization.

Pfizer's antiviral pills have been hailed by federal health officials as a potential game-changer in the fight against COVID-19, even before the Omicron variant was discovered. 

Paxlovid is a type of protease inhibitor that works to disrupt the process by which SARS-CoV-2 makes copies of itself in the body. It could be distributed and administered without the logistical hurdles facing other treatments like monoclonal antibodies, which must be injected by a provider. 

The company says it has submitted its new data to the Food and Drug Administration, which Pfizer's CEO has said was waiting for Paxlovid's final results to decide whether to grant emergency use authorization for the pills

Another oral antiviral pill called molnupiravir, developed by Merck and Ridgeback Biotherapeutics, had initially shown promising results in early data from its trials suggesting it halved the risk of hospitalization or death. But later results announced by the company from its final data found a modest risk reduction of only 30%. 

Molnupiravir's smaller-than-expected efficacy and worries over its risks dampened enthusiasm over that pill, which received a narrow backing by the FDA's outside advisers last month and has yet to be greenlighted by regulators. Some advisers urged the FDA to grant authorization for molnupiravir only until "an alternative agent comes along with better efficacy and fewer safety concerns."

Unlike molnupiravir, Pfizer's executives have said they do not expect Paxlovid to go before the FDA's advisers, arguing their large efficacy and low safety risks were more comparable to the monoclonal antibody treatments the FDA has authorized without the advisory panel's input. 

In both their trials, Pfizer said adverse events occurred at comparable rates between Paxlovid and the placebo.

"We don't think that there is at all the same type of risk for these drugs and, as anticipated, the tolerability profile was very good," Pfizer's Dr. Mikael Dolsten said at a recent conference with investors hosted by Wolfe Research.

Pfizer says Paxlovid will come as a set of three pills — two tablets of nirmatrelvir and and one tablet of ritonavir — taken together twice a day over the course of five days, soon after the first sign of infection. 

The Biden administration ordered a total 10 million courses of Paxlovid for Americans, the company said last month. Pfizer's CEO told The Wall Street Journal earlier this month that he expected they would only have a portion of Paxlovid's supply available to ship by the end of this year.

"If it is approved and we have it, it could be the next day. We will not have millions this month. We will have thousands. We will have hundreds of thousands in January. We will have millions in the first quarter," said Bourla. 

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