College administrators and government officials summoned students back to campus. Now, they are presiding over viral reservoirs poised to release a flood of infected undergraduates at Thanksgiving -- if they make it that far.

Schools have turned into de facto sanitariums: Covid-19 infections are sweeping student populations, though health departments are seeing relatively few hospitalizations or deaths so far. Colleges that tried to hold classes in person have had to send students into seclusion. Last week alone, the New Jersey Institute of Technology quarantined 300 people after the virus was found in their dorm’s wastewater, the University of Wisconsin at River Falls ordered all students to shelter in place after a surge in cases, and Florida State University’s football coach announced he had tested positive.

With many schools planning to end their semesters at the holiday, students will disperse across the country, and some will bring the disease with them.

“This is beyond our wildest nightmares,” said Gavin Yamey, a physician who directs Duke University’s Center for Policy Impact in Global Health. “It has been a debacle, a national catastrophe and, in many ways, you could consider it a third wave. The third wave is a university reopening wave. It was a self-inflicted national wound.”

Universities were bleeding revenue when they called students back for the fall semester, facing cuts as tuition and fees plunged. Some plowed ahead with lucrative football programs, despite their potential to draw crowds. But as students returned, infection rates increased. Many schools are now running out of space to house those who tested positive. Administrators are struggling to keep infections contained as students venture off campus for coffee or hang out at bars and parties.

“If infected students go home, there is a risk that they could seed outbreaks all around the country -- outbreaks that are ultimately caused by the university reopening,” said Yamey.