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Pfizer's Covid antiviral pill may cut severe illness by 89 percent

The drugmaker said its studies of the pill were so successful that it stopped clinical trials early.

The drugmaker Pfizer said Friday that clinical trials of its experimental Covid-19 pill have been so successful in preventing people from becoming hospitalized or dying from the virus, that it's stopping the studies early in the hope that the general public might benefit.

The antiviral pill, which is combined with a low dose of an HIV drug called ritonavir, can reduce hospitalizations or deaths from Covid-19 by up to 89 percent among high-risk patients, Pfizer said in a news release.

High-risk patients include the elderly, as well as people with underlying health conditions, such as obesity or type 2 diabetes.

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Albert Bourla, Pfizer’s chief executive, called the drug a potential “game-changer” in a statement.

“These data suggest that our oral antiviral candidate, if approved by regulatory authorities, has the potential to save patients’ lives, reduce the severity of Covid-19 infections, and eliminate up to nine out of ten hospitalizations.”

Pfizer only released its data in a press release; it did not publish the full data from the clinical trial. Dr. John Sanders, chief of infectious diseases at Atrium Health Wake Forest Baptist in North Carolina, said it will be important for outside experts to pore over and scrutinize the results.

Still, Sanders called the preliminary information “remarkable.”

“The availability of an oral antiviral that can reduce the risk of hospitalization and death in high risk patients by 89 percent will have a major impact on how we treat Covid-19,” he wrote in an email to NBC News.

Early diagnosis of Covid-19 would be key. Pfizer said that its antiviral was most effective within the first three days of symptoms. Side effects, according to Pfizer, were mild to moderate, and comparable to those who got the placebo.

The results were so significant, Pfizer said that it would “cease further enrollment into the study due to the overwhelming efficacy demonstrated," and planned to ask the Food and Drug Administration to authorize the drug combination “as soon as possible.”

The drug would be marketed in the U.S. under the name Paxlovid. It would be given in pill form, twice a day, for five days.

If ultimately authorized, it would likely be the second antiviral pill in use in the U.S. in which newly infected people could take at home to help prevent severe illness.

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The Pfizer news comes a day after the United Kingdom cleared use of an antiviral medication developed by Ridgeback Biotherapeutics and Merck. The pill, molnupiravir, will be marketed under the brand name Lagevrio in the U.K., and prescribed for people who have mild to moderate cases of Covid-19, as well as people who have at least one risk factor for developing the most severe outcomes of the illness.

In October, Merck asked the Food and Drug Administration to authorize molnupiravir. The company previously reported that the pill cut Covid-19 hospitalizations and deaths in half among those in the earliest stages of illness.

Advisors to the FDA are scheduled to meet Nov. 30 to discuss emergency authorization of the Merck pill.

The U.S. government is expected to absorb the cost for both medications, estimated to be about $700 per course of treatment.

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