Restaurants Are the Riskiest Places You Can Go Right Now

Limiting capacity to 20% could dramatically reduce infections

Photo: Dan Gold via Unsplash

Using cellphone data, researchers have developed a new computer model that shows which indoor places, aside from people’s homes, drove the most Covid-19 infections in major U.S. cities this spring. The verdict? Restaurants, gyms, coffee shops, and hotels were the riskiest places for transmitting SARS-CoV-2.

Their report, published in the journal Nature on November 10, also calls for restricting capacity at these places in lieu of complete lockdowns.

“Restaurants are by far the riskiest, about four times riskier than the next category, which are gyms and coffee shops, followed by hotels,” Jure Leskovec, PhD, an associate professor of computer science at Stanford University and senior author on the paper, said during a press briefing on Tuesday.

To make the model, computer scientists used anonymized geolocation data collected between March to May from 98 million Americans living in 10 major cities: Atlanta, Chicago, Dallas, Houston, Los Angeles, Miami, New York City, Philadelphia, San Francisco, and Washington, D.C. That data showed where people went in the course of a day, how long they stayed there, and how crowded those places were. The researchers then merged that information with demographic and epidemiological data.

The resulting model predicted that a small number of locations, such as full-service restaurants, accounted for a large majority of infections. For example, in the Chicago metropolitan area, just 10% of the places people visited accounted for 85% of the predicted infections. The infections predicted by the model largely matched actual Covid-19 cases in the cities studied.

The study backs up the idea that most Covid-19 transmissions happen at “superspreader” sites, like restaurants or places of worship, where people remain in close quarters for an extended period of time. The researchers recommend capping the occupancy of indoor venues at 20% of its maximum capacity. Doing so could reduce new infections by over 80%, they predict.

The research also helps explain why minority and low-income people are disproportionately being affected by the virus. Researchers found that people in lower-income neighborhoods with fewer white residents were not able to reduce their mobility as much as people in whiter, higher-income neighborhoods. In addition, the places that lower-income groups attended were more crowded, which increases the risk of infection.

“Our model predicts that one visit to a grocery store is twice more dangerous for a lower-income individual compared to a higher income individual,” Leskovec said.

The authors think reopening businesses with lower occupancy caps will benefit disadvantaged groups the most. “Because the places that employ minority and low-income people are often smaller and more crowded, occupancy caps on reopened stores can lower the risks they face,” study co-author David Grusky, PhD, a Stanford sociology professor, said in a university statement. “We have a responsibility to build reopening plans that eliminate — or at least reduce — the disparities that current practices are creating.”

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Emily Mullin

Emily Mullin

Former staff writer at Medium, where I covered biotech, genetics, and Covid-19 for OneZero, Future Human, Elemental, and the Coronavirus Blog.