In the absence of FDA-approved pharmacological therapies, convalescent plasma infusion has rapidly emerged as a notable emergency therapy for severe cases of COVID-19. However, due to the emergency conditions under which this treatment has been practiced, little effort has been placed in characterizing the properties of the donor plasma and the clinical status of the COVID- 19 patients that can most benefit from the infusion. We have assembled a multidisciplinary team that leverages linked blood donation and blood transfusion programs at Robert Wood Johnson University Hospital and state-of-the-art resources for the study of antibody responses and plasma markers of COVID-19 severity. This team proposes to conduct a study that relates donor plasma properties (antibody titers and functions, and antigen targets) and recipient's clinical status (including peripheral blood cell immunophenotypes and various plasma markers of COVID-19 severity) to the success of convalescent plasma infusion. The new knowledge resulting from our plan will guide the development of rational clinical practice guidelines and the design of convalescent plasma clinical trials.