This study aims to address the following three objectives:

Longitudinal evaluation of the development of CMI responses in response to SARS-CoV-2 Vaccine: T cells isolated from the blood of COVID-19 vaccine recipients will be evaluated for their functionality in response to vaccine antigens. The temporal and functional properties of CMI responses will be correlated with the humoral or antibody responsiveness. CMI responses will be measured in vaccine recipients prior to vaccination to determine whether the presence or functionality of pre-existing responses to common cold coronaviruses (CCCs) or previous SARS-CoV-2 infections affect the development of CMI responses to the COVID-19 vaccine.

Identification of cellular and soluble factors that influence vaccine responsiveness:

While it is known that poor clinical outcomes in COVID-19 patients are strongly associated with markers of systemic inflammation, the influence these systemic markers will have on COVID-19 vaccine responsiveness is not clear. Using systems biology approaches, the investigators will perform comprehensive profiling of cellular immune subsets, inflammatory signatures to identify determinants influencing the development of CMI responses to the vaccine.

Examine variability of immune and viral genes and their relationship to vaccine-induced immune responses: Human leukocyte antigen (HLA), T cell receptor (TCR) and B cell receptor (BCR) proteins are highly genetically diverse and critical to the development of protective immunity. The investigators will perform HLA sequencing on whole blood-derived DNA samples and TCR and BCR sequencing on sorted, SARS-CoV2 vaccine antigen-specific T cells and B cells, respectively, to assess how different sequence combinations impact the CMI responses to vaccine.