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News Flash—Pfizer’s COVID-19 Pill, Paxlovid, Looks Like a Winner

“If all goes well with the FDA review, the hope is that PAXLOVID could be prescribed as an at-home treatment to prevent severe illness, hospitalizations, and deaths.”

- Dr. Francis Collins, director, National Institutes of Health


“All I’d say is, Yahoo!”

- Mark Denison, M.D, Professor of Pathology, Microbiology, and Immunology, Vanderbilt University, virologist working on drugs for SARS-CoV-2



Just three weeks ago, I posted a Germ Gems “News Flash”: “Fluvoxamine: An Oral Drug for COVID-19 That’s Effective, Safe, and Cheap.” Today’s News Flash is on another breakthrough oral drug for treatment of outpatients with early COVID-19—Paxlovid.

The skinny on Paxlovid. In early November, scientists published their findings in Science, “An oral SARS-CoV-2 M(pro) inhibitor clinical candidate for the treatment of COVID-19.” A few days later, Pfizer announced interim results from a large phase 2/3 clinical trial showing that when their drug, Paxlovid, was taken within 3 days of developing symptoms of COVID-19, the pill reduced by 89% the risk of hospitalization or death in adults at high risk of progressing to severe illness. At the recommendation of the clinical trial’s monitoring committee and in consultation with the U.S. Food and Drug Administration (FDA), Pfizer halted the study based on the strength of the positive interim findings.


Pfizer’s antiviral pill is a protease inhibitor. Originally named PF-07321332 or just 332 for short, Paxlovid inhibits a viral protease that creates other proteins needed by SARS-CoV-2. On November 16, Pfizer submitted the data to the FDA for Emergency Use Authorization (EUA) of Paxlovid for people who are at increased risk of hospitalization because of age or underlying medical conditions. (Pfizer is also testing Paxlovid in people at low risk of severe outcomes. The drug might even be effective against other coronaviruses that cause the common cold.)

Another antiviral pill. As I mentioned in my October 29 Germ Gems post on Fluvoxamine, Merck and Ridgeback Pharmaceuticals is producing another promising antiviral pill—Molnupiravir. Molnupiravir causes a mutation that stops the virus from replicating. It recently was approved for use in the U.K. and is under evaluation by the FDA for EUA.

Cost considerations. The costs of Pfizer’s Paxlovid and of Merck’s Molnupiravir have not been published. It is unlikely, however, that they would be in reach of people living in low- or middle-income countries (LMIC) given that even a 10-day course of Fluvoxamine at $4 would be a stretch for these people. It was therefore encouraging to read this announcement in the November 16th New York Times, “Pfizer Will Allow Its Covid Pill to Be Made and Sold Cheaply in Poor Countries.” Merck is undertaking a similar strategy to make Molnupirivir cost-effective in LMIC countries.


The Biden Administration is planning to pay more than $5 billion for a stockpile of Paxlovid, enough for about 10 million courses of treatment. The federal government has also committed to buy about 3.1 million courses of Molnupiravir for $2.2 billion.


These kinds of investments in antiviral drugs for LMIC by the pharmaceutical industry in partnership with the U.S. government are unusual, but not unprecedented. Launched in 2003, the U.S. President's Emergency Plan for AIDS Relief (PEPFAR) is the largest commitment by any nation to address a single disease in history. It received bipartisan support from nine U.S. congresses and three presidential administrations. The generosity of the American people made PEPFAR possible. As of September 30, 2020, PEPFAR had saved over 20 million lives. Perhaps, the commitment of the U.S. to stockpile Paxlovid and to buy millions of courses of molnupiravir is the beginning of another such remarkable humanitarian initiative. I certainly hope so.

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Main Page images courtesy of Shuxian Hu, MD. Dr. Hu is a scientist in the Neuroimmunology Research Laboratory at the University of Minnesota.

 

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