Mandate the vaccine, not masks

With the rise of the delta variant and a rapid increase in Covid-19 cases, the US Centers for Disease Control and Prevention is calling on vaccinated people to wear masks indoors again in places where the virus is quickly spreading. At least some school districts will likely require masks this fall. Local governments, from Massachusetts to California, are reviving mask mandates.

A year ago, requiring masks as cases spiked would have been an obviously smart decision. Mask mandates work, and for most of 2020, they were among the best methods we had to stop the spread of Covid-19. But...