The urgent need for phased university reopenings to mitigate the spread of COVID-19 and conserve institutional resources: A modeling study

Rennert, Lior; Kalbaugh, Corey; McMahan, Christopher; Shi, Lu; Colenda, Christopher C

Introduction: Recent outbreaks of COVID-19 in universities across the United States highlight the difficulties in containing the spread of COVID-19 on college campuses. While research has shown that mitigation strategies such as frequent student testing, contact tracing, and isolation of confirmed and suspected cases can detect early outbreaks, such mitigation strategies may have limited effectiveness if large outbreaks occur. A phased reopening is a practical intervention to limit early outbreaks, conserve institutional resources, and ensure proper safety protocols are in place before the return of additional students to campus. Methods: We develop dynamic compartmental transmission models of SARS-CoV-2 to assess the impact of a phased reopening and pre-arrival testing on minimizing outbreaks (measured by daily infections) and conserving university resources (measured by isolation bed capacity). We assume that one-third of the student population returns to campus each month as part of the phased reopening, and that pre-arrival testing removes 90% of infections at the semester start. We assume an on-campus population of N = 7500, an active COVID-19 prevalence of 2% at baseline, and that 60% of infected students require isolation for an average period of 11 days. We vary the reproductive number (Rt) between 1.25 and 4 to represent the effectiveness of alternative mitigation strategies throughout the semester, where Rt is constant or improving throughout the semester (ranging from 4 to 1.25). Results: Compared to pre-arrival testing only or neither intervention, phased reopening with pre-arrival testing reduced peak daily infections by 6% and 18% (Rt=1.25), 44% and 48% (Rt=2.5), 63% and 64% (Rt=4), and 72% and 74% (improving Rt), respectively, and reduced the proportion of on-campus beds needed for isolation from 10%-25% to 5%-9% across different values of Rt. Conclusion: Phased reopening with pre-arrival testing substantially reduces the peak number of daily infections throughout the semester and conserves university resources compared to strategies involving the simultaneous return of all students to campus. Phased reopenings allow institutions to improve safety protocols, adjust for factors that drive outbreaks, and if needed, preemptively move online before the return of additional students to campus, thus preventing unnecessary harm to students, institutional faculty and staff, and local communities.