Colleges and universities are places of social interaction. Every university is a community, with its students composing a social ecosystem. Students come together to attend classes and tutorials, study with one another, work on group projects together, engage in recreational activities, eat, and commune. When done in small groups, these activities pose little risk of infection with proper precautions. But with these activities and large gatherings, the risk of disease is high.
When more than a third of US colleges and universities opened their campuses at the start of August, viral outbreaks naturally followed. Large universities like the University of North Carolina Chapel Hill (UNC) and the University of Notre Dame had to fully close.
Just after a week of in-person classes, UNC found 130 novel cases in students, and 5 in employees.
Near the end of the month, UNC had 756 confirmed cases.
By August 26, there were about 26,000 new cases across 750 colleges and universities in the US.
Another problem is that the virus can spread very quickly in places of gathering—dorms and off-campus residences—between asymptomatic students.
Expecting young people to take personal responsibility by wearing a mask as often as possible and practicing social distancing is not a good plan; behavioral research shows that young adults are most likely to take risks.
It is up to institutions to implement every precautionary measure they can. In this case, the best precautionary measure is to keep campuses closed for in-person classes in the fall semester.