The population tactics are blunt instruments, necessary for isolating hot spots like New York and Seattle. Other places may be able to rely more on individual interventions, which cause less disruption and economic damage. Yet every state should be taking steps such as encouraging social distancing and preparing to expand hospital capacity. Some states and cities that haven’t seen as many cases yet—such as New Orleans—have been too slow to take the threat seriously…

By the end of next week, the U.S. will have the capacity in place to screen more than 75,000 people a day. South Korea tested 1 in 160 of its people and deployed technology to identify people who were infected and trace contacts. The U.S. should do the same.

Another step: serological surveillance, which means blood tests to detect antibodies developed to fight the novel coronavirus. These antibodies confer immunity and can reveal whether a person has been exposed. If a sizable portion of a local community has some protection, authorities can be more confident in relying on less invasive measures. Once deployed, serological tests are cheap, straightforward, and easy to scale.