CD8A and COVID-19: The result showed a clear trend that patients with COVID-19 at convalescence stages (that is, clinical phases 6 and 7) had similar abundance distribution of CD8+ T cells over the development trajectory to healthy donors (clinical phase 0); in contrast, patients at disease stages (that is, clinical phases 1–5) tended to aggregate together, showing enrichment of CD8+ T cells in the high-exhaustion state (Extended Data Fig. 4g).