Evaluating the durability and cross-reactivity of SARS-CoV-2 immunity elicited by COVID-19 vaccines

COVID-19, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has advanced rapidly from initial clinical observations in late 2019 to a global pandemic. Safe and effective vaccines offer our best opportunity to control spread of infection, but limited availability of vaccine doses and rapid emergence of viral variants of concern that may evade vaccine-elicited immunity are major concerns in Canada and globally. "Partial" immunity elicited by one dose of vaccine may not protect some individuals, such as elderly adults, from infection by these new viral strains; however, we have an incomplete understanding of immune factors that may help to identify individuals or populations that remain at higher risk despite receiving the vaccine. Our project will compare the immune response in younger and older adults following one and two doses of COVID-19 vaccine. We will characterize the diversity of antibody-producing B cells generated following vaccination and link genetic features of these cells to each individual's ability to neutralize viral variants of concern. Our results will provide new information about vaccine-elicited immune responses and inform ongoing efforts to protect the most vulnerable members of our population.