Key Points Question Are surveillance testing and quarantine still important for limiting virus transmission on college campuses where the student population is completely vaccinated against SARS-CoV-2? Findings In this decision analytical model study of 5000 simulated undergraduates, if 100% were vaccinated with 90% vaccine effectiveness, surveillance testing and quarantine were not associated with a substantial reduction in infections. However, if vaccine effectiveness was reduced to 75%, weekly surveillance testing was associated with a substantial reduction in the number of infections; at 50% vaccine effectiveness, surveillance testing and quarantine were associated with a marked reduction in the estimated number of infections. Meaning The study results suggest that surveillance testing and isolation of positive cases may remain important mitigation strategies on university campuses with a vaccinated student body with only modest erosion of vaccine effectiveness, while quarantining contacts offers limited added benefit over surveillance testing alone and may be effectively replaced by an increased testing cadence of reported contacts. Importance The importance of surveillance testing and quarantine on university campuses to limit SARS-CoV-2 transmission needs to be reevaluated in the context of a complex and rapidly changing environment that includes vaccines, variants, and waning immunity. Also, recent US Centers for Disease Control and Prevention guidelines suggest that vaccinated students do not need to participate in surveillance testing. Objective To evaluate the use of surveillance testing and quarantine in a fully vaccinated student population for whom vaccine effectiveness may be affected by the type of vaccination, presence of variants, and loss of vaccine-induced or natural immunity over time. Design, Setting, and Participants In this simulation study, an agent-based Susceptible, Exposed, Infected, Recovered model was developed with some parameters estimated using data from the 2020 to 2021 academic year at Duke University (Durham, North Carolina) that described a simulated population of 5000 undergraduate students residing on campus in residential dormitories. This study assumed that 100% of residential undergraduates are vaccinated. Under varying levels of vaccine effectiveness (90%, 75%, and 50%), the reductions in the numbers of positive cases under various mitigation strategies that involved surveillance testing and quarantine were estimated. Main Outcomes and Measures The percentage of students infected with SARS-CoV-2 each day for the course of the semester (100 days) and the total number of isolated or quarantined students were estimated. Results A total of 5000 undergraduates were simulated in the study. In simulations with 90% vaccine effectiveness, weekly surveillance testing was associated with only marginally reduced viral transmission. At 50% to 75% effectiveness, surveillance testing was estimated to reduce the number of infections by as much as 93.6%. A 10-day quarantine protocol for exposures was associated with only modest reduction in infections until vaccine effectiveness dropped to 50%. Increased testing of reported contacts was estimated to be at least as effective as quarantine at limiting infections. Conclusions and Relevance In this simulated modeling study of infection dynamics on a college campus where 100% of the student body is vaccinated, weekly surveillance testing was associated with a substantial reduction of campus infections with even a modest loss of vaccine effectiveness. Model simulations also suggested that an increased testing cadence can be as effective as a 10-day quarantine period at limiting infections. Together, these findings provide a potential foundation for universities to design appropriate mitigation protocols for the 2021 to 2022 academic year. This decision analytical model study examines the use of surveillance testing and quarantine in a fully COVID-19–vaccinated university student population.
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