Without the lockdown measures taken by state and local governments, the number of U.S. coronavirus cases would have been 35 times higher, says a new study published in Health Affairs.

The study evaluates the impact of four measures taken in the U.S. to slow the spread of COVID-19 from March 1 to April 27, 2020: bans on large social gatherings, public school closures, the closing of entertainment-related businesses and shelter-in-place orders. The results imply the pandemic would have spread 10 times faster without shelter-in-place orders, resulting in 10 million cases by April 27 rather than one million, and that the U.S. would have seen 35 million cases by that date without any of the four measures.

The study finds that the closing of entertainment-related businesses (restaurants, movie theaters, gyms) and shelter-in-place orders resulted in a dramatic reduction in COVID-19 cases, while bans on large gatherings and school closures seemed to have a much milder impact. The authors said it’s possible the latter policies may have displaced social interaction rather than reducing it—for example, school closures may have led families to spend more time at parks or to use day care centers. In addition, many of the largest events, such as college and professional sports, were already being cancelled before the measures took place.

“Our results suggest that light measures don’t work, and strong measures do, but they don’t really say anything about intermediate measures—like opening restaurants at reduced capacity or allowing socialization with masks,” said one of the study’s authors, Charles Courtemanche, a professor at the University of Kentucky’s Gatton College of Business and Economics. “Since we don’t know what each intermediate step towards reopening will do, it makes sense to go one step at a time and look carefully for signs that the rate of spread is picking back up.”

The study: Strong Social Distancing Measures in the United States Reduced the COVID-19 Growth Rate