In the message sent to students and the university community, school officials said over 50 COVID-19 cases were detected in the past 48 hours, with a substantial number of cases among students living on-campus, distributed across multiple residence halls.
"We expect this number to increase," the message said.
"I was supposed to have practice later today, but it got canceled, so I had no idea this was coming," said Maguire Pesci, University of Chicago student.
Those who have tested positive are in isolation, following university protocols, but many of the cases might have been linked to one or more off-campus fraternity parties held over the last week, school officials said.
The school is currently working on contact tracing. According to the university, the cases likely came from off-campus social gatherings.
"I'm proud I didn't participate, but just the fact that it did happen was a bit disappointing, said Luke Kalaydjian, University of Chicago student.
"Definitely not totally surprising. I mean it's college students, a lot of college students who are not having a normal college experience, trying to like get some semblance of that, but you know actions have consequences," said Saira Munshani, University of Chicago student.
Due to the majority of the 65 and above population being vaccinated, Illinois continues to see an uptick of cases among 18-to-39-year-olds in Chicago. The positivity rate among ages zero-to-17-year-olds is higher than the state and city average.
"With the doubling of cases in Illinois over the last several weeks, similarly, we've seen a doubling of cases here at Lurie Children's," said Dr. Larry Kociolek, infectious disease specialist at Lurie Children's Hospital.
Dr. Kociolek said COVID-19 variants are contributing to pediatric cases as they are in the adult population.
School officials said this is the biggest cluster of cases to reach the university since the start of the academic year.
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As a result, students living in residence halls must observe a new stay-at-home period of seven days, beginning immediately and lasting through April 15. The order could be extended, officials said. Students can briefly leave their residence halls to get food, attend medical appointments, or go for a short walk for exercise.
Undergraduate classes will also be fully remote for at least seven days, starting Thursday. In-person graduate classes may continue, the university said. The order also requires students to only leave their dorms for a brief walk, a medical appointment or to get food.
University of Chicago students said the university made a the right decision despite the inconvenience of the stay-at-home order.
"A of schools have had spikes. It's not abnormal, and so I think if we handle it well right now, then hopefully it will not be a problem," Munshani said.
The university asked anyone who has recently attended a party or unmasked gathering to be tested immediately.
"We are hopeful that taking swift, comprehensive steps now should address this outbreak and allow us to conclude the academic year safely. We may need to consider additional steps if there is further spread of COVID-19, including placing further restrictions on in-person activities for Spring Quarter or scaling back planned College Convocation events," school officials said.