Modelling SARS-CoV-2 transmission in a UK university setting (preprint)

ABSTRACT

Background: The higher education system in the United Kingdom comprises a large student population. Around 40% of school leavers attend university and individual universities generally host thousands of students each academic year. In the setting of the COVID-19 pandemic, bringing together these student communities presents questions regarding the strength of interventions required to control transmission. Prior modelling analysis of SARS-CoV-2 transmission within universities has usually adopted a compartmental modelling approach, whose projections suggest an almost inevitable likelihood of outbreaks. Methods: We constructed a network-based model to capture the interactions of a student population in different settings (housing, social and study). For a representative campus-based university, we ran a susceptible-latent-infectious-recovered type epidemic process, parameterised according to available estimates for SARS-CoV-2. Over the course of a single academic term, we investigated the impact on infection control of adherence to (or effectiveness of) isolation, test and trace measures, the additional use of room isolation as an intervention and supplementary mass testing. Results: Incorporating uncertainty in the fraction of cases that are asymptomatic and their associated infectivity, in the absence of interventions our model estimated that 16% (2% - 38%) of the student population could be infected during the autumn term. In contrast, with full adherence to isolation measures and engagement with test-and-trace, predictions of the cumulative infection count were lower, 1.4% (0.4% - 5%). Irrespective of the adherence to isolation measures, on average a higher proportion of students resident on-campus became infected compared with students resident off-campus. Widespread adherence of interventions led to reductions in the average fraction of time those individuals adhering to measures were expected to be isolated, with room isolation as an additional intervention generating minimal benefits. The model found that a one-off instance of mass testing would not drastically reduce the term-long case load or end-of-term prevalence, but regular weekly or fortnightly testing could reduce both measures by more than 50% (compared to having no mass testing). Conclusions: Our findings suggest SARS-CoV-2 may readily transmit amongst a student population within a university setting if there is limited adherence to nonpharmaceutical interventions and there are delays present in receiving test results. Following isolation guidance and effective contact tracing both curbed transmission and reduced the expected time an adhering student would spend in isolation. Additionally, widespread adherence throughout the term suppresses the amount of unwitting asymptomatic transmission to family and community members in the students' domicile regions at the end of term.