INVESTIGATING THE UNDERLYING IMMUNLOGICAL MECHANISMS OF PREVIOUSLY INFECTED SARS-CoV-2 INDIVIDUALS IN A UNIVERSITY SETTING: A CROSS-SECTIONAL, SEROPREVALENCE STUDY

Abstract

Since December 2019, the COVID-19 pandemic has resulted in more than 770 million cases of the disease and over 6.9 million deaths worldwide. Although over 70% of the global population has been vaccinated against the coronavirus (over 13 billion doses administered), many individuals remain at risk of developing infection as novel sublineages of the Omicron variant continue to emerge. Gaps exist in our current understanding of COVID-19 disease pathogenesis in young individuals, particularly surrounding vaccine and infection-induced antibody durability and “long COVID-19". To address these gaps, we conducted a seroprevalence study at the Dalhousie University campus in Halifax, Nova Scotia, in the fall of 2022 and recruited N=77 students aged 18-35 years old. Rapid antigen testing and serum immunology were performed to measure the levels of previous infections on campus. I also assessed the serum concentration of twelve distinct blood biomarkers to characterize the long-COVID-19 immune response in this cohort. The sensitivity of rapid antigen testing was also compared to the gold standard RT-qPCR. My results suggest that young individuals mount a robust humoral immune response to COVID- 19, and experience elevated levels of biomarkers associated with endothelial disruption during long-COVID-19 (i.e., ICAM-1 and VCAM-1). It is also evident that the COVID-19 nucleocapsid protein remains detectable up to 270 days post infection, indicative of mechanisms of viral persistence. Finally, I show that rapid antigen testing is comparable to RT-qPCR at detecting asymptomatic COVID-19 infections. This study provides a better understanding of the SARS- CoV-2 immune response in young individuals (18-35 years) and also a framework for the predisposing biomarkers associated with long-COVID-19 in this cohort.