a, Timeline of COVID-19, showing detection of SARS-CoV-2 in sputum, nasopharyngeal aspirates and feces but not urine, rectal swab or whole blood. SARS-CoV-2 was quantified by rRT-PCR; cycle threshold (Ct) is shown. A higher Ct value means lower viral load. Dashed horizontal line indicates limit of detection (LOD) threshold (Ct = 45). Open circles, undetectable SARS-CoV-2. b, Anteroposterior chest radiographs on days 5 and 10 following symptom onset, showing radiological improvement from hospital admission to discharge. c, Immunofluorescence antibody staining, repeated twice in duplicate, for detection of IgG and IgM bound to SARS-CoV-2-infected Vero cells, assessed with plasma (diluted 1:20) obtained at days 7–9 and 20 following symptom onset. d–f, Frequency (left set of plots) of CD27hiCD38hi ASCs (gated on CD3–CD19+ lymphocytes) and activated ICOS+PD-1+ TFH cells (gated on CD4+CXCR5+ lymphocytes) (d), activated CD38+HLA-DR+ CD8+ or CD4+ T cells (e), and CD14+CD16+ monocytes and activated HLA-DR+ natural killer (NK) cells (gated on CD3–CD14–CD56+ cells) (f), detected by flow cytometry of blood collected at days 7–9 and 20 following symptom onset in the patient and in healthy donors (n = 5; median with interquartile range); gating examples at right. Bottom right histograms and line graphs, staining of granzyme A (GZMA (A)), granzyme B (GZMB (B)), granzyme K (GZMK (K)), granzyme M (GZMM (M)) and perforin (Prf) in parent CD8+ and CD4+ T cells and activated CD38+HLA-DR+ CD8+ and CD4+ T cells. Gating and experimental details are in Extended Data Fig. 3.