Restaurants and gyms were spring ‘superspreader’ sites. Occupancy limits could control Covid, new study predicts

Restaurants and gyms were spring ‘superspreader’ sites - STAT Using cellphone data, researchers have identified the indoor public places most responsible for the spread of Covid-19 in the spring. Elizabeth Cooney STAT

Using cellphone data from 1 in 3 Americans, researchers have identified the indoor public places most responsible for the spread of Covid-19 in the spring, and they argue that sharply limiting the occupancy of these locales — chiefly restaurants, gyms, cafes, hotels, and houses of worship — could control the raging pandemic without resorting to lockdowns.

Their analysis also explains how disparities in risk contribute to the disproportionate disease burden borne by people of color who have been less able than higher-income white people to work remotely and who tend to visit grocery stores and other places that tend to be smaller and more crowded than those in white neighborhoods.

“It corresponds to what we thought from the beginning, that there are certain activities that lead to spread more than other activities,” said Amesh Adalja, a senior scholar at the Johns Hopkins Center for Health Security who was not involved in the study. “When you are thinking of targeted public health interventions, it’s important to focus on those activities where that’s occurring and not being overly blunt and blocking and stopping all activities that may not necessarily have been a major contributor to spread.”

Mining mobile phone data, scientists tracked 98 million people’s hourly movements from March 1 to May 2 to places they visited regularly, and then mapped their movements to nearly 533,000 locations onto models of infectious disease spread. The simulated transmission rates accurately predicted actual daily case counts in neighborhoods of 10 large metropolitan areas, including Chicago, New York City, and San Francisco. That allowed them to identify which “superspreader” venues pose the greatest risk, which socioeconomic factors matter, and what works to diminish the danger.

“Our results suggest that infection disparities are not the unavoidable consequence of factors that are difficult to address in the short term, like differences in preexisting conditions,” Jure Leskovec of Stanford and co-authors wrote in their paper published Tuesday in Nature. “On the contrary, short-term policy decisions can substantially affect infection outcomes by altering the overall amount of mobility allowed and the types of [places] reopened.”

In Chicago, for example, 10% of the places people visited accounted for 85% of the predicted infections. Full-service restaurants, fitness centers, and places of worship had the highest overall risk for disease transmission, but that varied depending on the neighborhood. Across the 10 cities, snack bars and cafes were visited more often by people in high-income neighborhoods, but risk of disease transmission was higher in these businesses located in lower-income neighborhoods. ...