Pfizer says its antiviral pill is very effective in treating Covid

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Pfizer announcement Friday that his pill to treat Covid-19 had been found in a key clinical trial be very effective in preventing serious illness in people at risk who received the drug soon after showing symptoms, making it the second antiviral pill to be shown to be effective against Covid.

The drug appears to be more effective than a similar offering from Merck, which is awaiting federal clearance. The Pfizer pill, which will be sold under the brand name Paxlovid, reduces the risk of hospitalization or death by 89% when given within three days of the onset of symptoms.

Pfizer said that an independent expert board overseeing its clinical trial recommended the study be stopped early because the drug’s benefits for patients had proven to be so compelling. The company said it plans to submit the data as soon as possible to the Food and Drug Administration to seek permission to use the pill in the United States.

“The results truly exceed our wildest dreams,” said Annaliesa Anderson, an executive at Pfizer who led the drug’s development. She expressed hope that Paxlovid “can have a big impact in helping all of our lives get back to normal and see the pandemic end.”

The arrival of a new class of easy-to-use pills that dramatically reduce hospitalizations could help lift the curtain on the most serious phase of the pandemic, at least in wealthy countries where most adults have been vaccinated.

Pfizer and Merck pills, which can be dispensed at a drugstore and taken at home, are expected to affect many more people than monoclonal antibody treatments, which are usually given by intravenous infusion in a clinic.

The Pfizer treatment could be available in the next few months, although supplies are likely to be limited at first. Both Pfizer and Merck pills are intended for patients considered to be at high risk, such as those over the age of 60 or with conditions like obesity that make them more susceptible to the serious consequences of Covid.

President Biden said on Friday that the pill would be “another tool in our toolkit to protect people from the worst consequences of Covid,” but he stressed that the best approach was to prevent infections through vaccination.

Pfizer said it expects to be able to produce enough pills for more than 180,000 people by the end of this year and for more than 21 million people in the first half of next year. . Merck has also announced plans to increase production over the next year.

The US government is in negotiations with Pfizer to get enough pills for 1.7 million treatments, with an additional option for 3.3 million, according to a senior administration official. This is roughly the same amount the United States ordered from Merck. The government expects to pay around $ 700 per course of treatment for the two drugs, the official said.

A number of wealthy countries, including Britain and Australia, have also rushed to block Pfizer’s drug supplies.

Pfizer said it plans to offer the drug to poorer countries at reduced prices. The company is in talks with a United Nations-backed nonprofit, the Medicines Patent Pool, to enable the pill to be manufactured and sold at lower cost in these countries; Merck has already entered into a similar agreement.

The treatment consists of 30 tablets administered over five days. This includes 10 tablets of ritonavir, an older HIV medicine, which helps Pfizer’s medicine stay active longer in the body. (The course of treatment for Merck is 40 tablets over five days.)

So far, the pills have mainly been tested on high risk patients. But Pfizer is also conducting trials in low-risk patients and people in the same household as those infected with the virus.

The efficacy results announced on Tuesday included data from more than 1,200 adults in the United States and abroad who received either the Pfizer drug or a placebo pill after contracting Covid. The volunteers were recruited between July and September, when the Delta variant was spreading around the world. They were not vaccinated and had at least one characteristic that made them more at risk of becoming seriously ill from the virus, such as old age or obesity or diabetes.

Pfizer’s 89% efficacy figure comes from the group of volunteers who started treatment within three days of symptom onset. Including people who started treatment on the fourth or fifth day, the pill reduced the risk of hospitalization or death by 85%.

In contrast, the Merck pill was about 50 percent effective when given within five days of symptom onset, although the different designs and timing of the Pfizer and Merck trials make these comparisons imprecise. Monoclonal antibody treatments reduce hospitalizations and deaths by at least 70% in high-risk Covid patients, but these treatments are more expensive and cumbersome to administer.

The study volunteers who received the Pfizer pill reported mostly mild side effects at a slightly lower rate than those who received the placebo pill. This was a promising sign for the safety of the drug, indicating that the symptoms of Covid are likely more bothersome than any of the side effects of the pill.

The origins of the Pfizer pill go back 19 years to the SARS epidemic. At the start of last year, Pfizer began to change the design of the drug so that it could be used to fight Covid and taken as a pill rather than intravenously.

The drug from Pfizer belongs to the class of so-called protease inhibitors which are commonly used to treat HIV and hepatitis C. The drug is designed to prevent the coronavirus from replicating by blocking the activity of an enzyme key that the coronavirus uses to replicate inside cells.

Pfizer also said its studies show the drug to be safe and does not cause disturbing mutations. Some scientists have raised concerns about the Merck Pill, which works by inserting errors into the virus’s genetic code to prevent it from replicating. The Pfizer pill does not do that.

Britain, which on Thursday became the first government to allow Merck’s pill, recommended not to use it in women who are pregnant, breastfeeding or likely to become pregnant during treatment and for four days afterwards.

Carl Zimmer and Stephanie Nolen contributed reports.


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