The proven strategy for virus suppression relies on contact tracing through communities. The bulk of testing is initially aimed at symptomatic individuals in health care settings and likely hot spots, with additional testing in “critical contexts” like nursing homes, prisons and meatpacking plants susceptible to disease spread. All contacts of any positive case are traced until the chain of transmission yields zero positives. In a successful suppression surge, contact tracing turns up the vast majority of positive cases.

The U.S. strategy should start by breaking states down into colored zones, representing levels of outbreak: green is the safest, followed by yellow, orange and red. The counterintuitive trick is to focus on lower-incidence yellow and orange zones before higher-incidence red zones, because lower-incidence zones require less testing and tracing to stop community spread and can stay open with safety precautions during a surge.

Within a state, just a few months of surging testing and tracing can result in green zones — which means less than one new daily case for every 100,000 people. Once a zone falls into the green, people no longer have to fear outbreaks at school, church or work. To stay green, states maintain a minimum level of testing and tracing to identify and quash new infections before they spread.