Coronavirus disease 2019 (COVID-19) is an infectious disease caused by severe acute respiratory distress syndrome coronavirus 2 (SARS-CoV-2). The global pandemic that started in China in December 2019 has seen both development of vaccines in December 2020, and emergence of successive variants of the virus which alter the efficacy of the available vaccines. At this point in time, the correlates of susceptibility have not been adequately characterized, particularly in patients with compromised immunologic status. Reducing SARS-CoV-2 transmission, morbidity and mortality at both the individual and population level will require better understanding of immunity to this virus. The Serological Sciences Network (SeroNet) was established in 2020 as a consortium of institutions to explore the diagnostic and investigative laboratory science of immunity to SARS-CoV-2, and to prospectively track cohort populations for outcomes, with especial attention to post-vaccination outcomes in susceptible individuals. For this study, 11 of the SeroNet institutions have come together for a "Pooling Project" consisting of conducting real-world data (RWD) analysis using electronic medical record (EMR) data (4 institutions); conducting meta-analyses of the ongoing prospective cohort studies (8 institutions); and investigating heterogeneity in vaccine effectiveness according to age, social determinants of health (SDoH), common clinical risk factors, and laboratory-based correlates of immunohematologic function (4 institutions). This Feinstein (FIMR)/Northwell application is for the purposes of: (a) serving as lead institution for the RWD analyses of patients with autoimmune conditions (systemic lupus erythematosus, rheumatoid arthritis, inflammatory bowel disease); (b) serving as co-lead institution for the RWD analyses of patients with cancer; and (c) serving as co-lead institution for the meta-analysis of prospective cohort studies of patients with systemic lupus erythematosus. Northwell health is a nonprofit integrated healthcare network that is New York State's largest healthcare provider, and by patient volumes over the length of the pandemic, has been one of the top healthcare systems in the country for care of COVID-19 patients. Thanks to its in-system integrated laboratory network (Northwell Health Laboratories), extensive SARS-CoV-2 RWD is available, both for diagnostic (PCR) and serologic (Antibody) testing. This 2-year project will pursue both analysis of extant RWD, and monitoring of the relevant cohort populations over the course of the 2-year study