Universities across the country are announcing their intention to resume in-person classes despite the ongoing threat of a pandemic including some recent high-profile decisions. Colleges are proposing solutions like residential pods in dorms to balance physical distancing with the need for social contact or digital apps that trade-off privacy for contact tracing. These ideas could provide more flexibility in the future.
All three of us are educators who miss being in the classroom with our students, but we are also public health researchers, and these solutions all assume it is possible to reopen safely. So far, the evidence contradicts that. Every way we approach the question of whether universities can resume on-campus classes, basic epidemiology shows there is no way to "safely" reopen by the fall semester. If students are returned to campus for face-to-face instruction, the risk of significant on-campus COVID-19 transmission will be unmanageably and unavoidably high.
Most reopening efforts assume some degree of protection is conferred by students' younger age. But on-campus transmission does not stop at a university's gates and university communities (including undergraduate students) are more diverse than young people in perfect health. The potential for severe outcomes from COVID-19 is high and unpredictable. Though estimates of the fatality rate of COVID-19 are still being refined, some reliable studies place the age-adjusted case fatality rate at 0.5%, five times that of seasonal influenza. The risk of death among young adults falls unequally, being 5 to 9 times higher among Black, Hispanic, and indigenous young adults.
Death isn't the only worry: Clinicians are documenting heart, kidney, and neurological problems from coronavirus infection, and a recent analysis of patient experiences shows some cases continue experiencing symptoms for 50 days or longer. We still don't reliably know what risk factors lead to these severe outcomes, but activities like vaping — which is on the rise among college students — may increase risk, and health conditions such as obesity, which occurs in 16% of college students, are believed to increase the need for hospital admission and critical care from COVID-19. Without a well-defined risk rubric, cocooning the most vulnerable students, staff, and faculty while reopening is infeasible.
If acquiring COVID-19 remains risky, the question becomes whether universities can stop transmission on campus. The cardinal rule of a dangerous respiratory epidemic is to avoid unnecessary congregation. But campuses are a dense network of highly connected, clustered settings with intense social contact; students meet in dorms, classrooms and other common spaces. Diminishing connectivity through physical distancing can't eliminate long chains of transmission. Cutting a select few environments from the college experience as a "compromise" (e.g., distanced on-campus housing or repurposing dining halls as carryout) might distance students from each other, but probably not enough to stop the spread. A recent study on data from Cornell University showed even without the effect of dormitories, shared food facilities, and extracurricular activities, physical classes create fertile conditions for disease transmission on their own.
Another risk is that most interactions occur indoors. One experimental study showed SARS-CoV-2 viral particles can remain in the air for at least three hours and recirculate without significant airflow. Most traceable COVID-19 transmissions happened indoors: All 318 clusters of three or more COVID-19 cases in Chinese cities occurred in an indoor environment, and among eleven clusters of cases in Japanese cities, the chances of COVID-19 transmission were 19 times greater in a closed environment.
An investigation of large-scale outbreaks at a church and a choir practice and recent experiments also suggest situations with widespread voice projection — such as a physically distanced classroom — may increase transmission risk. While face coverings can meaningfully reduce the risk of respiratory transmission from the wearer to others, incorrect use or lack of perfect adherence can render surgical masks ineffective at stopping transmission. The popularity of bandannas and simple cloth masks — as medical masks are prioritized for front-line responders and essential workers — makes the efficacy of these interventions less certain or reliable. Moving outside can also reduce transmission compared to poorly ventilated space, but trying to teach and learn wearing masks in a spaced-out, outdoor setting will be more disruptive than the now-familiar setting of online classrooms.
Even with every evidence-backed mitigation option, there is no way to transmission-proof a physical classroom — let alone a dense, highly socially connected miniature city, interconnected with its host community. When outbreaks do happen, most public health experts agree the best COVID-19 response is to test widely and identify infected cases, isolate and treat them, trace the close contacts whom they might have infected and then quarantine those contacts. But COVID-19 is by nature resistant to this intervention in highly dense settings; the virus is highly infectious, with a relatively long period during which a person may be infectious but not yet showing symptoms.
University administrators should be prepared for several roadblocks that could make "test-trace-isolate" a gamble. It is not clear how available or accurate tests that will be most readily available are. Testing during the presymptomatic stage currently fails to identify a large fraction of cases: Recent meta-analysis showed four days before symptoms start the false-negative rate of testing is 100% (meaning you would miss all cases), reducing only to 38% on the day symptoms start. This means approximately a third of cases would be missed. Given that so much transmission happens in the presymptomatic stage, relying on testing for case confirmation would allow significant transmission. The success or failure of the test-trace-isolate strategy depends on high frequency and high capacity; most universities will be unprepared for that monumental effort, and without regular (e.g. weekly) testing of all students and faculty, cases will undoubtedly slip through the cracks.
Fever or symptom screening has been proposed by some organizations as a key for safe return. However, a large proportion of COVID-19 cases occur without infectious individuals showing symptoms. As a result, relying on symptoms to detect cases would allow significant transmission to continue. COVID-19 can be transmitted before a person becomes symptomatic, with a reasonable estimate that 44% of transmission occurs before symptom onset. In addition, 40 to 45% of positive cases have been found to be asymptomatic and are more likely among those of college or graduate student ages.
Once positive tests have been identified, their contacts must be traced and followed up with. For a disease as infectious as COVID-19, 70 to 90% of all contacts of an infected individual would have to be tested and quarantined, requiring significant resources. Universities face overwhelming limits of a test-trace-isolate approach and can't over-promise an outbreak response that might be unmanageable as circumstances turn dire.
While a semester away from campus is daunting, this isn't the end of the college experience as we know it. Thankfully, this pandemic will eventually come to an end through effective treatments, accelerated vaccine development and distribution, and sustaining the greatest reductions in social interaction possible.
Until then, universities must face facts that no perfectly executed test-trace-isolate strategy, innovative in-person classroom, or medically informed triage of student risk will be sufficient to guarantee zero on-campus mortality (let alone total outbreak prevention). Students have to trust that we're accountable and that no "acceptable losses" have entered the calculus of our response to a crisis that they — like us — are facing for the first time.
Bansal is an associate professor in the department of biology at Georgetown University. Kraemer is an associate professor at Georgetown University's department of health systems administration. Carlson is an assistant professor at Georgetown University who works at the Center for Global Health Science Security. This piece was written for The Washington Post.
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