Researchers who conducted a decision and cost-effectiveness study published today in JAMA Network Open have concluded that the safe reopening of US college campuses amid the COVID-19 pandemic this fall relies on every-other-day screening of asymptomatic students and strict compliance with physical distancing and infection-control protocols.
The study involved modeling a hypothetical cohort of 4,990 healthy college students and 10 with undetected, asymptomatic COVID-19 infections at the start of the semester.
Assuming a reproduction number (Rt) of 2.5 (meaning that a primary case of COVID-19 is infecting, on average, 2.5 other people) and daily screening with a test with 70% sensitivity, a test with 98% specificity detected 162 student infections and resulted in a mean isolation dorm daily census of 116 and resulted in 21 of 116 (18%) of students with confirmed positive results.
In contrast, screening every 2 days detected 243 infections and resulted in a mean daily isolation dorm census of 76 and 28 of 76 students (37%) with confirmed positive results. And screening every 7 days yielded 1,840 infections, a mean daily isolation dorm census of 121 students, and 108 of 121 students (90%) with confirmed positive results.
In all scenarios, testing frequency was more strongly tied to total infections than was test sensitivity. The Rt for daily testing was 3.5, whereas it was 2.5 at 2 days and 1.5 at 7 days, meaning that daily screening cost $910 per student per semester, versus $470 every 2 days and $120 every 7 days.
With every-other-day screening, the mean daily isolation dorm census fell because fewer tests were performed, and fewer false-positive results were generated. But less-frequent testing was also linked to greater spread of infection and a higher mean proportion of students with confirmed positive results in isolation. Weekly and symptom-based screening were associated with large increases in numbers of infected students in the isolation dorm.
Student, staff, community, financial considerations
Colleges pose a particularly thorny problem because they feature dorms with close quarters and shared spaces, communal dining, limited numbers of large classrooms and auditoriums, and a population eager to socialize. Thus, the authors said that the study results could be useful to the many schools that must either reopen their doors to students in the fall or suffer serious economic fallout.
They said that good management of both confirmed positive and false-positive test results consists of rapid detection, confirmation, isolation, and treatment of confirmed positive cases, which would require frequent screening with an even low-sensitivity test and an 8-hour turnaround time. The biggest obstacle to achieving this goal, the researchers said, is management of the large number of false-positive test results that would result from repeated screening for a low-prevalence condition.
"False-positive results threaten to overwhelm isolation housing capacity, a danger whose gravity increases with screening frequency," the authors wrote. "The specificity of the initial test will matter far more than its sensitivity."
But in the absence of a coronavirus vaccine, colleges must make do with the limited available options in a complex situation with many variables, which may mean that some schools may elect to offer only distance learning.
"In this analytic modeling study, screening every 2 days using a rapid, inexpensive, and even poorly sensitive (>70%) test, coupled with strict behavioral interventions to keep Rt less than 2.5, is estimated to maintain a controllable number of COVID-19 infections and permit the safe return of students to campus," the authors said. "This sets a very high bar—logistically, financially, and behaviorally—that may be beyond the reach of many university administrators and the students in their care."
They added that University presidents must also consider the downstream effects of their decisions on faculty, staff, and the community. "However, their first responsibility is to the safety of the students in their care," they said.
A multilayered university pandemic response
Jill DeBoer, MPH, director of the University of Minnesota Health Emergency Response Office and CIDRAP deputy director, said in an interview that every-other-day COVID-19 screening is not feasible with the limited availability of testing resources. "It would really take away from available resources for those who most need them," she said.
Instead, the University of Minnesota is following the Centers for Disease Control and Prevention's guidance and not doing mass testing. Instead, it is using targeted "smart" testing, the tenets of which were developed by CIDRAP, using the right infrastructure, test, test interpretation, and action to provide the most benefit to the community.
That includes testing symptomatic staff and students and asymptomatic people with known exposure to someone with COVID-19 and those linked to a cluster of three or more cases, per Minnesota Department of Health testing priorities. They will also test some asymptomatic people before certain medical procedures and public utility employees working on campus, at the utility's request.
On-campus testing resources will be prioritized for students and employees who use campus health services for primary care because testing is available in other primary care clinics throughout the state, DeBoer said.
She said that the most important thing is to take a multilayered approach consisting of informed individual decision making, daily health monitoring, staying home when ill, physical distancing, the use of personal protective equipment in clinical situations and face coverings outside of that setting, targeted testing, regular cleaning, supporting isolation and quarantine for those who need it, cooperating with contact tracing efforts, and rapidly adjusting plans as public health guidelines are revised. "They all have to be in place; testing is one component, but they all have to happen together," she said.
Above all, she added, colleges need to allow students, faculty, and staff to make choices based on their own health indicators, ensure that there are resources to support them in their choice, and remain flexible.
For example, DeBoer, who has an underlying medical condition, is teaching an undergraduate course 2 days a week in the fall. She has decided to teach the first day of lecture and discussions in a large auditorium that offers space for physical distancing and the second day of small-group discussions online, because physical distancing isn't conducive to those types of discussions. "But if I do a few [in-person] classes and it doesn't feel safe, it's important that I say 'this doesn't feel safe and we're going to switch.'"