Bars played a critical role in University of Wisconsin-Madison’s coronavirus outbreak this fall, a researcher from the Massachusetts Institute of Technology found.
Shortly after trips to a cluster of bars near Witte and Sellery residence halls spiked in early September, the two dorms saw large outbreaks of COVID-19, MIT economics professor and physician Jeffrey Harris found in a recent study.
Harris analyzed anonymized smartphone location data from late August through early October and compared it to COVID-19 infections in census tracts on and around UW-Madison’s campus.
Track COVID-19 in Wisconsin:See the latest numbers and trends
How to interpret COVID-19 data: What experts say about positive cases, deaths and hospitalizations
Nearly 3,000 UW-Madison students tested positive for the virus in that time frame, and at Witte and Sellery the virus spread quickly: about 20% of residents at the two dorms were infected.
The smartphone data showed that trips from Witte and Sellery to a nearby cluster of 20 bars in early September were “a significant determinant of infection rates,” Harris wrote.
Facing mounting cases, Chancellor Rebecca Blank paused in-person classes and ordered students to stay home Sept. 7. The school imposed lockdowns at Witte and Sellery on Sept. 9.
By early October infections were down, and the school was testing at a much higher rate than the surrounding Dane County.
“To its credit, the university accomplished the extraordinary task of squelching the outbreak within a matter of weeks, rather than capitulating to a call by the Dane County board of supervisors to close its residence halls and send its 31,000 students back home,” Harris wrote.
Blank clashed with Dane County Executive Joe Parisi over school’s response to the outbreak, defending her choice not to send students home. In late September, she urged local officials to step up enforcement at off-campus sites, such as bars, that are outside the school’s jurisdiction.
She said that cases would not decline until “agencies with enforcement authority take additional action.”
“You don’t need to look hard on social media to find a photo of long lines outside downtown bars or parties in large apartment buildings, or other places where 18- to 24-year-olds are gathering,” Blank wrote.
In his study, Harris found that residents of Witte and Sellery were nearly three times as likely to go to a cluster of 20 bars than residents of Ogg and Smith halls.
For every 10% increase in bar visits per capita, the incidence of COVID-19 cases per capita rose about 9%, Harris found.
Tracked visits to a cluster of 68 nearby restaurants and coffee shops did not show a strong relationship to infection rates like bars did, Harris found.
The practice of bar-hopping likely makes it much easier for the virus to spread, Harris said. Visiting several bars in one night means many more people could be exposed to an infected person.
“When there is high mobility between places, they may function effectively as one place,” he said.
While superspreader events at weddings, nursing homes, meatpacking plants and other large gatherings have received a lot of attention over the course of the pandemic, Harris said researchers and public health officials need to focus more on “the potential super-spreader effects of clusters and networks of places, rather than individual sites.”
Along with Witte and Sellery, the school quarantined two dozen fraternities and sororities in September.
Harris identified two major waves of outbreaks: first within Greek housing, underway even before classes began Sept. 2, and next at residence halls and nearby off-campus housing, but concentrated most heavily in Witte and Sellery. His research could not determine whether the first wave led to the second.
And while Harris did see a connection between trips to bars and outbreaks at fraternities and sororities, he could not rule out large parties at off-campus housing as a contributing factor as well.
UW-Madison students returned home for Thanksgiving and are finishing the semester remotely. They’ll return to in-person instruction in late January.