8 lingering questions about the new Covid pills from Merck and Pfizer

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,...