Workers in Freiburg, Germany, manufacturing Pfizer’s new antiviral drug, Paxlovid, in November.Credit...Pfizer

The Food and Drug Administration is expected to soon authorize a pill made by Merck and Ridgeback Biotherapeutics, called molnupiravir, which reduces the risk of hospitalization and death from Covid-19 by 30 percent if taken within five days of the onset of symptoms.

Another antiviral pill, developed by Pfizer, may perform even better. An interim analysis showed that the drug was 85 percenteffective when taken within five days of the start of symptoms. The F.D.A. could authorize it by year’s end.

Since the start of the pandemic, scientists have hoped for convenient options like these: pills that could be prescribed by any doctor and picked up at a drugstore.

And these two pills may be just the beginning. With the threat of Omicron and other variants looming, scientists say we will need an arsenal of drugs to deploy against new foes, especially if those variants erode the protection of existing vaccines.

Researchers across the world are designing new drugs from scratch, precisely targeting weak points in the molecular structure of the coronavirus. And others are testing whether pills work better in combination than when taken on their own.