People in New York City, Seattle, New Orleans and San Francisco are listening to orders to stay home, according to a report issued Monday by the US Centers for Disease Control and Prevention.
"When you put in these social distancing measures, they do seem to work," said study coauthor Kathleen Ethier, leader of the CDC's community mitigation task force for the Covid-19 response.
While there are early indications that social distancing has helped slow the spread of the coronavirus, experts warn that if people don't continue to adhere to the orders, the virus could surge again in some areas.
The CDC report looked at data in New York City, Seattle, New Orleans and San Francisco, four cities with substantial numbers of coronavirus patients early in the outbreak that mandated people stay at home in mid- to late-March.
The report found that, in all four cities, the percentage leaving home was close to 80% on February 26. By April 1, that declined between 20% and 40% in each city, with mobility decreasing each time a new social distancing order was issued, starting with bans on mass gatherings, and then later restaurant and school closures and finally stay at home orders.
"They didn't leave their home at any point for any reason. They didn't go outside. That's significant," Ethier said.
The CDC tracked mobility by looking at whether devices such as cell phones were brought more than 500 feet from the places they usually spend the night. Using anonymized publicly available data from a company called SafeGraph, the CDC looked at phones, tablets and watches belonging to between 3.6% and 6.4% of the population in each city.