The horror of the coronavirus data lag

Andy Slavitt, a health-care official in the Obama administration, theorized at the beginning of May that the U.S. won’t see the cumulative effect of any reopening spikes until June, because of the weeks it takes for one case to go from transmission to death. Crystal Watson, a professor and risk-assessment expert at Johns Hopkins University’s Center for Health Security, recently told the Associated Press that she expects the lag in the United States to be even longer: five to six weeks from when businesses reopen.

Those assessments have not stopped proponents of reopening from declaring victory in states that have already eased restrictions on businesses, such as Georgia, Texas, and Colorado. Two weeks after reopening, none of them has experienced dramatic spikes. Georgia, whose governor received the most intense blowback—including from me—seems to have kept its rate of transmission largely stable in the earliest days after lifting lockdown, according to estimates commissioned by The Atlanta Journal-Constitution, with about one new transmission resulting from every newly discovered infection. But because the state backdates many of its cases to when patients first had symptoms, it takes two weeks for case counts for any particular day to be completed. Public-health experts are largely in agreement that any changes observed right now, in Georgia or elsewhere, are the result of behavioral patterns from weeks before states began to reopen. In other words, any positive effects are the result of older restrictions, not recent leniency.