A new report from the Centers for Disease Control and Prevention presents an alarming picture of colleges’ effects on their communities’ coronavirus rates after welcoming students back for the fall term.
Over a six-week period straddling the start of those terms, counties that were home to large colleges that opened for in-person instruction saw a 56-percent increase in coronavirus-case rates, the analysis found. In contrast, during the same period, counties that were home to large colleges that went primarily online saw their case rates fall, by 18 percent. Counties not home to a large university — enrolling at least 20,000 students — had case declines of 6 percent.
The troubling findings appeared on Friday, as many colleges neared the start of in-person spring semesters at a much more dangerous moment than last fall for Covid-19 transmission. Nationally, coronavirus-case rates were much lower then. Now, each day brings historic death and hospitalization totals; several colleges have already delayed their in-person start dates.
When they do restart, colleges must do more to prevent transmission, said Lisa Barrios, who leads the School Fieldwork Unit of the CDC’s Covid-19 Emergency Response, and who worked on the analysis. “Colleges and universities with in-person classes should be considering ways that they can increase their mitigation efforts,” she told The Chronicle.
Many traditional-age students experience mild or no symptoms, and that can obscure the true impact of campus transmission on their communities. “We need to be extra-careful to not just think about the majority of the population on campus being relatively young and healthy adults,” she said, “but thinking about what that means for the greater community population, especially older adults, those who have underlying conditions that put them at increased risk for severe outcomes, and those who are at greater risk because of various other health disparities.”
It was already well known that many counties experienced case spikes when their local colleges opened for the fall term. The CDC’s data show the pattern was widespread, at least among the 101 college-hosting counties in its dataset. In addition, Barrios and her team compared those counties with “matched” counties — nearby counties that are similar in size and geography but aren’t home to a large college.
The comparison with “matched” counties helps to show that if students hadn’t returned to their college towns, the counties probably wouldn’t have experienced the heavy case rates that they saw, outside experts said. “The study is well done, and its results are convincing to me,” Jon Zelner, an assistant professor of epidemiology at the University of Michigan at Ann Arbor, wrote in an email.
Asked if the CDC’s numbers mean that colleges didn’t do enough to prevent cases among their students in the fall, Barrios said she couldn’t answer that question because the study covered only a sliver of America’s colleges. In addition, the CDC team didn’t examine each college’s anti-Covid strategy to determine if that had affected county case rates.
“It’s just clear, though, we need to be thinking about doing some more,” she said. She cited standard Covid-prevention strategies, including wearing masks, social distancing, limiting social gatherings, and testing and contact tracing. In line with CDC guidance, she recommended colleges not only test symptomatic students and the close contacts of those who test positive, but also do surveillance testing of people with no symptoms, in the case of an outbreak or high community case rates.
The CDC study still leaves some key questions unanswered about colleges’ culpability for worsening the pandemic in their communities in the fall, Zelner and others said. The data don’t distinguish between cases among students and cases in the community — numbers that can be difficult to come by on a large scale — so it’s hard to tell whether cases moved out from the campus into the community, or whether they remained contained at the college.
In addition, the CDC data cover 21 days after the colleges’ first day of fall instruction. What happened after that? It’s plausible that some colleges controlled initial outbreaks and kept case numbers down before the disease could spread to more vulnerable community members.
But Barrios said three weeks is more than enough time for an outbreak among students to spread to other people. She pointed to CDC scientists’ other work showing that case spikes among young adults ages 20 to 39 — not just college students — took an average of just nine days to lead to a spike among adults over age 60.
Either way, said Giles Hooker, a statistician at Cornell University, “it would be very interesting to see the follow-up in those counties for, say, Weeks 4 through 6.”
