Researchers at Stanford University in the United States have conducted a study showing that college campuses have an extremely high incidence of coronavirus disease 2019 (COVID-19) and that reopening them could initiate superspreading into neighboring communities.
The team’s modeling of COVID-19 outbreak dynamics across 30 campuses and their home counties revealed a high number of campus outbreaks during the first two weeks of class. These outbreaks tended to then spread into neighboring communities.
Of the 30 institutions studied, 14 saw infections spike, with peak seven-day incidence an order of magnitude larger than the nation-wide peaks that occurred during the first and second pandemic waves.
Many institutions failed to control the spread of the virus beyond campus and within just two weeks, 17 outbreaks had caused infections to peak within home counties.
However, most campuses quickly managed the outbreaks and rapidly reduced the number of new infections.
We anticipate that tight test-trace-quarantine strategies, flexible transition to online instruction, and – most importantly – compliance with local regulations will be critical to ensure a safe campus reopening after the winter break,” writes Ellen Kuhl and colleagues.
A pre-print version of the paper is available on the server medRxiv*, while the article undergoes peer review.
The question of whether to re-open is a topic of ongoing debate
The question of whether colleges and universities should reopen while the COVID-19 pandemic is still ongoing remains a topic of ongoing debate and major concern.
Many institutions that reopened in the fall experienced massive waves of infection and college campuses were quickly declared as the new pandemic hotspots.
With term having now ended and a long winter break ahead, it is essential to comprehensively review the fall and carefully evaluate the risks of campuses reopening, say the researchers.
What did the researchers do?
The team analyzed the outbreak dynamics of COVID-19 across 30 campuses and their home counties across the United States using a susceptible-exposed-infectious-recovered (SEIR) compartment model. A method called Bayesian inference was used to estimate the effective reproduction number (number of secondary infections resulting from a single infection) based on the institutes’ daily COVID-19 case reports throughout the fall of 2020.
By comparing the features of campus outbreaks with COVID-19 cases reports for the home counties, the team could assess whether the reopening of campuses correlated with outbreaks in the local community.
The first two weeks of class was a high-risk period
Of the 30 institutions studied, the number of infections spiked across 14 campuses within the first two weeks of class.
The maximum seven-day per 100,000 incidence within these institutions was well above 1,000 – an order of magnitude larger than the nation-wide peaks seen during the first and second pandemic waves (70 and 150, respectively).
Policymakers often consider a seven-day per 100,000 incidence of 50 as a threshold for high-risk counties, states, or countries. All 30 institutions included in the study had a maximum incidence that exceeded this value by two and even three orders of magnitude.
The highest maximum incidence (3,083) was observed for the University of Notre Dame, followed by the University of Arizona (2,700), and Clemson University (2,685).
Many institutes failed to control SARS-CoV-2 transmission beyond campus and within just two weeks, 17 outbreaks had caused infections to peak within neighboring communities.
Our results are a quantitative confirmation of the common fear in early fall that colleges could become the new hot spots of COVID-19 transmission,” writes the team.
Successful reopening relies on control measures
However, most campuses responded well to the outbreaks and managed to quickly reduce the reproduction number to well below one within two to three weeks.
For the majority of campuses, outbreak dynamics remained manageable throughout the entire fall, with narrow spikes of less than 300 cases per day. Neighboring communities were less successful at containing the spread of the virus.
“Our findings suggest that college campuses present a risk to initiate superspreading events, but, at the same time, should be applauded for their rapid responses to successfully manage local outbreaks,” says Kuhl and the team.
“Successful reopening relies on limiting the introduction of the virus during the initial weeks of the term, regular testing and rapid tracing, and the collective understanding of the importance of quarantine and isolation,” they advise.
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