Fig. 6

Scatter plots of early-stage biomarkers (≤ 2 weeks from symptom onset) versus late-stage IgG (≥ 5 weeks from symptom onset) in COVID-19 patients. Serum levels of cytokines IL-6 (A), IL-8 (B), TNF-α (C) at the early stage of ≤2 weeks from symptom onset are positively correlated with the response of IgG at the late stage of ≥5 weeks from symptom onset. Positive correlations with IgG responses were also observed for D-dimer (D), neutrophils (E), and C-reactive protein (F). Spearman’s correlation coefficients (r) and their p-values (P) are shown