This supplementary material provides additional data and analysis supporting the findings of a study on spontaneous, persistent, T cell-dependent IFN-γ release in patients who progress to Long Covid. The materials include figures, tables, and references that detail the methods, results, and statistical analyses used in the main study. Key points include: 1. **PBMCs from Long COVID Patients Produce More IFN-γ**: Unstimulated PBMCs from Long COVID patients produce significantly more IFN-γ compared to unexposed controls and those with acute COVID-19. 2. **No General T Cell Dysfunction in Long COVID Patients**: IL-2 release from PBMCs in Long COVID patients is not different from controls, indicating no general T cell dysfunction. 3. **IFN-γ Release Not Correlated with Acute COVID Severity**: Unstimulated IFN-γ release in Long COVID patients does not correlate with the severity of acute COVID disease. 4. **Impact of Long COVID on Immune Cell Composition**: Flow cytometry analysis shows changes in immune cell composition in Long COVID patients compared to healthy controls. 5. **PBMCs from Long COVID Patients Produce More Pro-Inflammatory Cytokines**: PBMCs from Long COVID patients produce more pro-inflammatory cytokines compared to healthy controls. 6. **IL-2 Production in Response to Spike Peptide Stimulation**: IL-2 is produced in response to spike peptide stimulation after vaccination in patients with Long COVID. The supplementary material also includes detailed descriptions of the experimental procedures, gating strategies, and statistical analyses used to support the findings.This supplementary material provides additional data and analysis supporting the findings of a study on spontaneous, persistent, T cell-dependent IFN-γ release in patients who progress to Long Covid. The materials include figures, tables, and references that detail the methods, results, and statistical analyses used in the main study. Key points include: 1. **PBMCs from Long COVID Patients Produce More IFN-γ**: Unstimulated PBMCs from Long COVID patients produce significantly more IFN-γ compared to unexposed controls and those with acute COVID-19. 2. **No General T Cell Dysfunction in Long COVID Patients**: IL-2 release from PBMCs in Long COVID patients is not different from controls, indicating no general T cell dysfunction. 3. **IFN-γ Release Not Correlated with Acute COVID Severity**: Unstimulated IFN-γ release in Long COVID patients does not correlate with the severity of acute COVID disease. 4. **Impact of Long COVID on Immune Cell Composition**: Flow cytometry analysis shows changes in immune cell composition in Long COVID patients compared to healthy controls. 5. **PBMCs from Long COVID Patients Produce More Pro-Inflammatory Cytokines**: PBMCs from Long COVID patients produce more pro-inflammatory cytokines compared to healthy controls. 6. **IL-2 Production in Response to Spike Peptide Stimulation**: IL-2 is produced in response to spike peptide stimulation after vaccination in patients with Long COVID. The supplementary material also includes detailed descriptions of the experimental procedures, gating strategies, and statistical analyses used to support the findings.