(NEXSTAR) – A new study on COVID-19 in big U.S. cities found that a small number of often-frequented places are responsible for the transmission of a large majority of infections – and suggests limiting crowd size at these venues might be the best way to fight the virus.
The study, which was published in the journal Nature, used cellphone data to track the hourly movement of 98 million people and model how the virus spread as they visited sporting goods stores, restaurants, churches and car dealers, among other locations.
According to the study, restaurants opening at full capacity generated the greatest increase in COVID-19 cases, followed by gyms, cafes and hotels and motels.
“Our model predicts that a small minority of “superspreader” POIs (points of interest) account for a large majority of infections” according to the study, which found that limiting crowd size at those specific venues – as opposed to a full economic shutdown – could be an effective and more viable approach to battling the virus.
Using data from Chicago, the model found that fully opening restaurants May 1 would have resulted in an additional 600,000 cases, while opening gyms would have caused another 149,000 infections. If the city had opened all points of interest completely, 3.3 million more people would have contracted the virus.
Keeping those places open but reducing the maximum occupancy at 30%, however, brought the number of projected additional cases down to 1.1 million. If the cap was at 20%, that number would have been 650,000 cases, according to the study.
The model accurately predicted the actual number of confirmed cases recorded in Chicago between March 8 and April 15, the study’s authors said.
The model also supported what has been previously established, that people in disadvantaged racial and socioeconomic groups experience higher infection rates.
“We find that disadvantaged groups have not been able to reduce mobility as sharply” and the cellphone data shows the “points of interest” they visit are “more crowded and therefore higher-risk.”
The research has limitations, however, in that it only used data from big cities, not rural areas or suburbs. It also did not account for infections tied to other place such as schools, nursing homes or prisons.
The researchers, who are from Northwestern University, Stanford University, Cambridge and Mark Zuckerberg-funded Biohub, said they hope their work “can inform more effective and equitable policy responses to COVID-19.”