SARS-CoV-2 Seroprevalence in a University Community: A Longitudinal Study of the Impact of Student Return to Campus on Infection Risk Among Community Members

BackgroundReturning university students represent large-scale, transient demographic shifts and a potential source of transmission to adjacent communities during the COVID-19 pandemic. MethodsIn this prospective longitudinal cohort study, we tested for IgG antibodies against SARS-CoV-2 in a non-random cohort of residents living in Centre County prior to the Fall 2020 term at the Pennsylvania State University and following the conclusion of the Fall 2020 term. We also report the seroprevalence in a non-random cohort of students collected at the end of the Fall 2020 term. FindingsOf 345 community participants, 19 (5{middle dot}5%) were positive for SARS-CoV-2 IgG antibodies at their first visit between 7 August and 2 October. Of 625 student participants who returned to campus for fall instruction, 195 (31{middle dot}2%) were positive for SARS-CoV-2 antibodies between 26 October and 23 November. Twenty-eight (8{middle dot}1%) community participants returned a positive IgG antibody result by 9 December. Only contact with known SARS-CoV-2-positive individuals and attendance at small gatherings (20-50 individuals) were significant predictors of detecting IgG antibodies among returning students (aOR, 95% CI: 3{middle dot}24, 2{middle dot}14-4{middle dot}91; 1{middle dot}62, 1{middle dot}08-2{middle dot}44; respectively). InterpretationDespite high seroprevalence observed within the student population, seroprevalence in a longitudinal cohort of community residents was low and stable from before student arrival for the Fall 2020 term to after student departure. The study implies that heterogeneity in SARS-CoV-2 transmission can occur in geographically coincident populations. FundingThe Pennsylvania State University Office of the Provost, Social Science Research Institute, Huck Institute for the Life Sciences, and Clinical and Translational Science Institute; National Institutes of Health. RESEARCH IN CONTEXTO_ST_ABSEvidence before this studyC_ST_ABSThis study was initiated in Spring of 2020, during the pandemic but prior to the return of students to US universities. There was no prior research on the consequences of the return to in-person university instruction on SARS-CoV-2 transmission. While the explicit case of transmission of SARS-CoV-2 between student and resident communities was poorly understood at the start of this study, there is a well-established literature that has documented the role that large population movements, consistent with the return of students to campuses, play in the introduction and maintenance of pathogen transmission or diseases. Several studies documented the role of travelers in the introduction of SARS-CoV-2 to populations. The return of students to colleges and universities creates the potential for SARS-CoV-2 introduction and transmission with a sustained increase in population size, density, and mixing. No prior study has considered the long-term transmission consequences of such demographic change on the pre-influx population. We searched PubMed, medRxiv, bioRxiv, and Google Scholar between May 2020 and September 2020. We used search terms "seroprevalence", "anti-SARS-CoV-2", "IgG", "COVID antibodies" and "university", "college". Several modeling studies had been conducted to project likely prevalence of anti-SARS-CoV-2 antibodies in student and resident populations resulting from the return of students to in-person instruction in the Fall 2020 term in the US and UK. Several studies conducted after September 2020 described the county-level incidence of SARS-CoV-2 in counties that contain colleges and universities. None of these studies specifically disaggregated the incidence of COVID in resident and student populations. Added value of this studyThere is clear evidence that in-person university instruction is correlated with high incidence in students and higher incidence in counties with colleges and universities in counties those without such institutions. However, this is the first study to specifically quantify the change in seroprevalence in non-student residents associated with the return of students to in-person instruction in a large university setting. Despite high COVID-19 incidence in the student population, seroprevalence in the community resident cohort was low and stable from before student arrival for the Fall 2020 term until after student departure. The results of this study highlight the potential for significant heterogeneity in incidence in geographically coincident sub-populations. Implications of all the available evidenceThe influx of students into college and university towns reflects a significant increase in population size and density that could result in increases in COVID-19 risk in surrounding communities. Despite the potential risk, it is possible that SARS-CoV-2 transmission may lag behind in surrounding communities This implies the potential to minimize the transmission of SARS-CoV-2 from high prevalence sub-populations with targeted interventions. Future work should investigate the relative efficacy of specific measures to reduce risk of transmission between subpopulations and guide communities with high levels of episodic migration and similar high-density subpopulations.