As colleges prepare to open—or not open—their campuses to students for the upcoming school year, scientists have come up with a scenario they say could limit the spread of the coronavirus. Testing every student every two days and quickly isolating those with positive results should avoid widespread SARS-CoV-2 infections on college campuses, whereas only testing students with symptoms would not, according to a modeling study published Friday (July 31) in JAMA Network Open.
The researchers used an initial scenario with 5,000 students on campus, 10 of whom were carrying the coronavirus. They varied how many people each student infects, the frequency of testing, and the sensitivity of the tests used—that is, how often they correctly identify a person as infected.
If students were tested each day with a test with a sensitivity of 70 percent, 162 would become infected over the course of an 80-day semester, the model projected; testing every two days would result in 243 new infections. In contrast, weekly testing would result in 1,840 new infections. That sensitivity is on the low end for tests, but the authors assume such tests would be cheaper than higher-quality versions.
Study coauthor A. David Paltiel tells The Washington Post that the frequency of testing is more important than its accuracy, because testing repeatedly would eventually identify positive cases. He also notes that deciding not to reopen campuses, and instead have students stay home for the semester, is not without risk. “The problem doesn’t go away simply because you don’t reopen campus,” he says.
In remarks to UPI, Paltiel recognizes that high-frequency testing of all students will be challenging to implement. “This sets a high bar—logistically, financially and behaviorally—that may be beyond the capacity of many universities, and everything that could go wrong has to go right to avert an outbreak,” he tells the wire service. “However, any school that cannot meet these minimum screening standards or maintain uncompromising control over good prevention practices has to ask itself if it has any business reopening.”
The modeling did not uncover any scenarios in which waiting to act until students displayed symptoms would contain the virus, and Paltiel tells CNN that doing so would be “like a fire department that only responds to calls once they have verifiable evidence that the house has already burned to the ground.”
In a commentary accompanying the study, other researchers suggest that frequent testing may not be necessary if students test negative before being allowed back on campus and if multiple precautions are taken to stop the virus from getting onto campus or spreading once there, such as mask wearing and social distancing and erecting physical barriers. They estimate that with such measures and testing every four weeks, their college, Vassar, would only see 79 student infections out of 2,500 people over the course of a semester. “Thus, before diverting resources from other interventions to testing every 2 days, we should consider a broader perspective,” they write. “The best-prepared campuses will implement a set of interlocking strategies that together aim, first, to reduce the influx of COVID-19 from outside and, second, to limit its spread once on campus.”
Paltiel tells Inside Higher Education, “I’m a little bit distressed by how confident Vassar is to weed out infection by re-entry and to keep the students inside that walled garden and to regulate that behavior. As someone with an engineering background, I think often about the fact that we build bridges not to withstand the weight we expect but to withstand the weight several times we expect.”