Fig. 1

The lymphocyte subset alterations in severe COVID-19 patients. Representative flow cytometry plots for T cell, B cell, and NK cell (A), CD4⁺ T cell (B), and CD8⁺ T cell (C) for severe COVID-19 patients. Representative flow cytometry plots for T cell, B cell, and NK cell (E), CD4⁺ T cell (F), and CD8⁺ T cell (G) for mild COVID-19 patients. The comparison of absolute counts (G) and proportions (H) of lymphocyte subset between severe and mild COVID-19 patients. The differences were compared using the Mann-Whitney U test. *P < 0.05 and **P < 0.01; NS, not significant