Should the Delta variant change the U.S. pandemic playbook?

A more contagious variant of the coronavirus, known as Delta, has spread to more than 80 countries around the world and now accounts for more than half of COVID-19 cases in the United States.

First identified in India, Delta is believed to be between 40 and 60 percent more transmissible than the Alpha variant that was first identified in the United Kingdom, which itself was substantially more contagious than the original coronavirus strain that started the global pandemic. The Delta variant has fueled outbreaks around the globe and forced a growing number...