Fig. 1: Longitudinal characterization of immunological recovery in COVID-19 severity groups.

a, Distribution of patient sampling across five COVID-19 severity groups over 1 yr post first SARS-CoV-2-positive swab (group A) or symptom onset (groups B–E). Group A, mild asymptomatic, n = 18 (3 M and 15 F), WHO clinical progression score = 1; group B, mild symptomatic, n = 40 (9 M and 31 F), WHO score = 2–3; group C, moderate without supplemental oxygen requirement, n = 48 (25 M and 23 F), WHO score = 4; group D, moderate with supplemental oxygen given as maximal respiratory support, n = 39 (25 M and 14 F), WHO score = 5); and group E, severe with assisted ventilation, n = 69 (52 M and 17 F), WHO score = 6–10. Repeat samples totaled 73, 148, 132, 114 and 288 across groups A–E, respectively. HCs were sampled at baseline day 0 (n = 60, 34 M and 26 F). Each point represents a time point of blood collection; samples from patients who later died are rimmed in black. Vertical dashed lines, the span of time windows used in all analyses (that is, days 0–14, 15–30, 31–90, 91–180, 181–270 and 271–360 post onset). The time range of follow-up questionnaire submission (Q1, 3–5 months and Q2, 9–10 months) is indicated (top). b,c, Distribution of age (b) and sex (c) across groups A–E and the HCs defined as in a. The demographics for the deceased patients alone are shown (bottom). d, Absolute cell count differences (fold change) between the patients in severity groups A–E and HCs during the analyzed time windows. e,f, Number of pDCs (e) and the ratio of activated/naive CD8⁺ T cells (f) in severity groups A–E and HCs. The gray band represents the interquartile range (IQR) of the HCs; the y axis is shown as a logarithm base ten scale. Box plots show the minimum value, 25th percentile, median, 75th percentile, maximum value and outliers beyond 1.5× the IQR. d–f, *P < 0.05, **P < 0.005 and ***P < 0.0005; significance of group effect (per COVID-19 severity group, per time window relative to the HCs) as calculated by linear regression of the log₂-transformed counts (or ratio) with correction for age and sex; no multiple testing correction was applied. DP, deceased patient.