Questions linger about the new Covid pills from Merck and Pfizer

8 lingering questions about the new Covid pills from Merck and Pfizer The new Covid pills from Merck and Pfizer offer a ton of promise. But there’s plenty we still don’t know about how well they work. Erin Mershon STAT

The past two months have brought extremely good news in the fight against Covid-19. Two different oral treatments have proved effective at both preventing people newly diagnosed with Covid-19 from entering the hospital and from dying.

“We’re accelerating our path out of this pandemic,” President Biden said after data on the second Covid pill became available. The wide availability of oral drugs could make Covid-19 less lethal, making it less risky for people to return to in-person work and to their normal lives.

The first results, from Merck and Ridgeback Therapeutics, were released in October and will be considered by an advisory panel to the Food and Drug Administration in December. That could lead to an emergency use authorization in the U.S. by the end of the year. That drug, molnupiravir, reduced hospitalizations by 50% and prevented deaths entirely a large randomized clinical trial when it was given within five days of when symptoms began. The pill is given as a five-day course during which patients take a total of 40 pills.

In November, Pfizer announced that its Covid pill, Paxlovid, reduced hospitalizations by 89% and also prevented deaths in its own large randomized study. As with the Merck drug, Paxlovid is given as a five-day course. It must be given with a second medicine, a booster, called ritonavir, which is made by AbbVie, another large drug firm. The Pfizer regimen involves taking 30 pills over a five-day period.

Though the topline results are similar, the medicines could have different risks and benefits. The companies have only issued data in press releases, not scientific articles, and doctors need to know a lot more about both. Here is an overview of what we still don’t know about the Covid pills and when we might learn it.   ...