Immune Responses to COVID-19 Infection or Vaccination

1. Background and Overview Aditxt, Inc, in collaboration with researchers at Stanford University, has laboratory-developed tests (LDTs) for simultaneously monitoring anti-SARS-COV2 antibodies (IgG, IgA, and IgM) directed against 3 different SARS-CoV-2 antigens (RBD, S1, and NP) as well as assessing SARS-CoV-2 neutralizing antibody activity.

These tests are currently being offered routinely to the public as the AditxtScoreTM at Aditxt's CLIA certified, CAP accredited clinical laboratory in Richmond, VA. Aditxt also performs these tests for research and development purposes at a facility in Mountain View, CA. The AditxtScore provides an ideal platform for real- world investigations of immune responses to SARS-CoV-2 exposure as well as to the COVID-19 vaccines.

The overall purpose of this observational cohort study is to characterize COVID-specific immune responses to SARS-CoV-2 exposure or COVID vaccination in a real-world setting. Participants will be asked to provide blood samples (either a normal venous blood draw, a few drops of blood obtained with a small finger-stick device, or both), as well as saliva or nasal swab sample at a series of visits. Subjects will receive results of the testing that is approved for routine clinical use (i.e., their AditxtScore), while residual samples from each visit will be stored for future testing. These efforts will support ongoing AditxtScore test development and enhance the effectiveness of its interpretation - aiding efforts to maximize benefits of clinical laboratory testing in the pandemic response. 2. Objectives • To characterize immune responses (e.g., magnitude/strength and temporal dynamics of antibody generation, class switching, and antibody persistence) following exposure to the SARS-CoV-2 virus or COVID-19 vaccination.

• To investigate between group (eg vaccine vs. natural exposure) and within group (i.e., individual variation) differences in immune responses.

• To determine the relationship between AditxtScore components and neutralizing antibody activity and other potential correlates of protection, and to describe possible clinical correlates of immune response characteristics.

• To support test development activities such as determining appropriate clinical cutpoints, analyte stability, and comparability of results from different sample types (e.g., venous blood draw vs fingerstick blood drop, nasal swab vs. saliva collection). These activities will support refinement of existing tests as well as development of future tests (e.g. COVID-19 specific memory B cell, T cell, and NK cell responses). 3. Study Procedures 3a. Subject Recruitment Subject recruitment will consist primarily of word-of-mouth efforts of study personnel (e.g. friend and family networks) and other interested parties in the local community (e.g. a handful of local physicians). No broad advertising campaign is anticipated, though a study announcement flyer describing the study opportunity will be used to support recruitment efforts. Potential subjects will be directed to call Aditxt to schedule a time to come to the laboratory and learn more about the study.