Project 467067

The COVID-19 pandemic has resulted in over 250 million cases and over five million deaths worldwide. To combat the global crisis, large-scale vaccination efforts have expedited and redefined the timeline for vaccine rollout. Despite the initially high rates of vaccine efficacy (~95% against the alpha variant) following full-vaccination (two doses), many individuals remain at risk, regardless of vaccination status. Instances of fully vaccinated individuals contracting SARS-CoV-2 are often referred to as Breakthrough Cases. Recent data from the Center for Disease Control (CDC) suggests that the elderly (80 years), immunocompromised, and individuals with underlying health conditions are at the greatest risk of a breakthrough infection. The underlying mechanisms of breakthrough cases are currently unknown, and therefore, are the central focus of my research proposal. Gaps exist in our understanding of the immunological mechanisms involved in long-term vaccine induced immunity, particularly in pertinence to breakthrough infections and in at-risk groups. Therefore, I propose to explore levels of antibody (humoral) and T cell mediated (cellular immunological) SARS-CoV-2 immune responses in a fully-vaccinated, elderly Nova Scotian population (80 years) and a cohort with BMI 30 and Type II Diabetes. We will isolate PBMCs to compare virus reactive CD8+ memory T cells expressing activation markers as well as developing ELISA assays targeted at S-specific IgG and IgA, angiotensin converting enzyme 2 (ACE2), and pseudovirus neutralization from SARS-CoV-2 alpha, delta, and omicron variants and other newly emerging variants of concern. Results will be used to develop a rapid diagnostic test to identify individuals who have maintained vaccine-induced immunity.