Review 4: "Reopening universities during the COVID-19 pandemic: A testing strategy to minimize active cases and delay outbreaks."

Allali Mériem

doi:doi:10.1162/2e3983f5.2e2aa59a

Pre-entry screening of students entering universities for COVID-19 may help limit the spread of COVID-19, but further analysis is warranted to know the true impact. The modeling is too simple for a complex situation, and should take into account other critical factors.

by Allali Mériem

Published onSep 22, 2020

Reopening universities during the COVID-19 pandemic: A testing strategy to minimize active cases and delay outbreaks

by Lior Rennert, Corey Andrew Kalbaugh, Lu Shi, and Christopher McMahan

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Published on Jul 07, 2020
www.medrxiv.org

Description

Background: University campuses present an ideal environment for viral spread and are therefore at extreme risk of serving as a hotbed for a COVID-19 outbreak. While active surveillance throughout the semester such as widespread testing, contact tracing, and case isolation, may assist in detecting and preventing early outbreaks, these strategies will not be sufficient should a larger outbreak occur. It is therefore necessary to limit the initial number of active cases at the start of the semester. We examine the impact of pre-semester NAT testing on disease spread in a university setting. Methods: We implement simple dynamic transmission models of SARS-CoV-2 infection to explore the effects of pre-semester testing strategies on the number of active infections and occupied isolation beds throughout the semester. We assume an infectious period of 3 days and vary R0 to represent the effectiveness of disease mitigation strategies throughout the semester. We assume the prevalence of active cases at the beginning of the semester is 5%. The sensitivity of the NAT test is set at 90%. Results: If no pre-semester screening is mandated, the peak number of active infections occurs in under 10 days and the size of the peak is substantial, ranging from 5,000 active infections when effective mitigation strategies (R0 = 1.25) are implemented to over 15,000 active infections for less effective strategies (R0 = 3). When one NAT test is mandated within one week of campus arrival, effective (R0 = 1.25) and less effective (R0 = 3) mitigation strategies delay the onset of the peak to 40 days and 17 days, respectively, and result in peak size ranging from 1,000 to over 15,000 active infections. When two NAT tests are mandated, effective (R0 = 1.25) and less effective (R0 = 3) mitigation strategies delay the onset of the peak through the end of fall semester and 20 days, respectively, and result in peak size ranging from less than 1,000 to over 15,000 active infections. If maximum occupancy of isolation beds is set to 2% of the student population, then isolation beds would only be available for a range of 1 in 2 confirmed cases (R0 = 1.25) to 1 in 40 confirmed cases (R0 = 3) before maximum occupancy is reached. Conclusion: Even with highly effective mitigation strategies throughout the semester, inadequate pre-semester testing will lead to early and large surges of the disease and result in universities quickly reaching their isolation bed capacity. We therefore recommend NAT testing within one week of campus return. While this strategy is sufficient for delaying the timing of the outbreak, pre-semester testing would need to be implemented in conjunction with effective mitigation strategies to reduce the outbreak size.

RR:C19 Evidence Scale rating by reviewer:

Potentially informative. The main claims made are not strongly justified by the methods and data, but may yield some insight. The results and conclusions of the study may resemble those from the hypothetical ideal study, but there is substantial room for doubt. Decision-makers should consider this evidence only with a thorough understanding of its weaknesses, alongside other evidence and theory. Decision-makers should not consider this actionable, unless the weaknesses are clearly understood and there is other theory and evidence to further support it.

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Review:

This article discusses strategies for screening and mitigating covid 19 in a US university campus with approximately 25,000 students. I agree that campuses may be important places for the spread of the virus. Concerning the period of contagiousness of the virus, the authors use a period of 3 days. This seems rather short when compared with generally assumed values.
The study of the literature seems rather indicated a much longer period of contagiousness of about 14 days as mentioned in one of our articles. The authors should justify their choice and give references. What could be the consequences on the cases of active infections, the occupancy rate of isolation beds, or contact cases if the duration of contagiousness was 10 days or 14 days?
Another concern is the fact that the study focused only on students and not on all university staff. Students have contact with university staff and other people in the surroundings of the university. This important fact should be taken into account.

Review 4: "Reopening universities during the COVID-19 pandemic: A testing strategy to minimize active cases and delay outbreaks."

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