The U.S. Food and Drug Administration has granted emergency-use authorization to two prescription COVID pills that patients with mild-to-moderate infections can take at home and that, to varying degrees, can prevent the worst outcomes. Serious illness. Hospitalization. Death.

Doctors were counting on the new pills, from New Jersey pharma Merck and Pfizer in New York, to help keep people out of hospitals as the Delta and Omicron lineages of the SARS-CoV-2 drive back-to-back waves of infections.

But there are signs the Merck and Pfizer pills won’t be as safe, effective and widely available as some initially thought they might be. “They may not be the panacea we hoped,” Irwin Redlener, the founding director of Columbia University’s National Center for Disaster Preparedness, told The Daily Beast.