Pfizer antiviral drug could nearly end deaths from COVID-19, company study suggests

A new drug being developed by Pfizer offers the possibility of nearly putting an end to deaths from COVID-19.

When given within five days of the onset of symptoms, the antiviral therapy called Paxlovid, prevented almost 90% of deaths from COVID-19 compared to a placebo, a Pfizer study found.

By the end of the year, the company plans to complete two other studies of the pill, which is given twice a day for five days. Pfizer plans to submit the study data as part of its ongoing rolling submission to the Food and Drug Administration as soon as possible.

It’s not yet clear how much the treatment would cost or how many doses could be rapidly made available, assuming it receives clearance from regulatory agencies.

Pfizer’s pill compares favorably to a similar one being developed by Merck and Ridgeback Biotherapeutics that cut in half the hospitalization and death rate for COVID-19.

Both the Pfizer and Merck-Ridgeback drugs were so effective that independent boards reviewing their data stopped the studies early.

On Thursday, Merck and Ridgeback received authorization to provide their drug, molnupiravir, in the United Kingdom to adults with confirmed mild-to-moderate COVID-19 who have at least one risk factor for developing severe disease.

This made it the first authorized at-home treatment for COVID-19. In the U.S., only one drug, remdesivir, has been approved for use in hospitalized patients with COVID-19, though the steroid dexamethasone and other treatments approved for other purposes are also used in treatment.

Monoclonal antibodies, which can help stop the progression of COVID-19 infections, are authorized for emergency use in people recently diagnosed with COVID-19 who are at high-risk for severe disease. These are generally available as infusions, though they can also be delivered as multiple-dose shots.

Molnupiravir, originally created by researchers at Emory University in Atlanta along with colleagues at University of North Carolina at Chapel Hill, is given as four pills taken twice a day for five days.

An FDA advisory committee is scheduled to meet later this month to discuss the companies’ request for an emergency use authorization for molnupiravir.

In a statement Thursday, the U.K.’s Health and Social Care Secretary Sajid Javid called molnupiravir a “gamechanger for the most vulnerable and the immunosuppressed.”

Merck and Ridgeback expect to produce 10 million treatment courses of molnupiravir by the end of this year.

Both Pfizer and Merck-Ridgeback are entering into advance purchase agreements with countries to provide their pills once regulatory agencies sign off on them.

Merck and Ridgeback already have a purchase agreement with the U.S. government to provide 1.7 million treatment courses of molnupiravir at just over $700 each. For comparison, an antiviral used against the flu, called Tamiflu, costs just under $100 per treatment and its generic sells for about $21.
In the newly published trial result for Paxlovid, Pfizer showed an 89% reduction in risk of COVID-19-related hospitalization or death among more than 1,200 volunteers, half of whom received a placebo. All participants were adults and had at least one characteristic or underlying medical condition associated with an increased risk of developing severe COVID-19.

Nearly 7% of those who received a placebo ended up hospitalized, compared to just 1% of those who got the active drug. Ten of the people in the placebo group died. None of those who received the active drug died.

An independent data monitoring committee, in consultation with the FDA, decided to end enrollment in the study, because the drug has been shown to be so effective. The company had planned to enroll 3,000 people.

Most side effects are mild and were comparable between those who received the active drug and the placebo, according to a Pfizer news release.

Paxlovid is a protease inhibitor – the same type of drug that turned HIV into a manageable disease – which blocks replication of the virus. The drug comes in a blister pack with two pills of Paxlovid and one of an antiviral, ritonavir, which enables Paxlovid to remain active longer at higher concentrations. Patients take two packs a day for five days.