While the economic and social costs have been enormous, it’s not clear that the lockdowns have brought significant health benefits beyond what was achieved by people’s voluntary social distancing and other actions. Some researchers have credited lockdowns with slowing the pandemic, but they’ve relied on mathematical models with assumptions about people’s behavior and the virus’s tendency to spread—the kinds of models and assumptions that previously produced wild overestimates of how many people would die during the pandemic. Other researchers have sought more direct evidence, looking at mortality patterns. They have detected little impact.

In a comparison of 50 countries, a team led by Rabail Chaudhry of the University of Toronto found that Covid was deadlier in places with older populations and higher rates of obesity, but the mortality rate was no lower in countries that closed their borders or enforced full lockdowns. After analyzing 23 countries and 25 U.S. states with widely varying policies, Andrew Atkeson of UCLA and fellow economists found that the mortality trend was similar everywhere once the disease took hold: the number of daily deaths rose rapidly for 20 to 30 days, and then fell rapidly.

Similar conclusions were reached in analyses of Covid deaths in Europe. By studying the time lag between infection and death, Simon Wood of the University of Edinburgh concluded that infections in Britain were already declining before the nation’s lockdown began in late March. In an analysis of Germany’s 412 counties, Thomas Wieland of the Karlsruhe Institute of Technology found that infections were waning in most of the country before the national lockdown began and that the additional curfews imposed in Bavaria and other states had no effect.