IL10 and COVID-19: Eventually, age (OR: 0.660; 95% CI: 0.525–0.830), BMI (OR: 1.700; 95% CI:1.301–2.222), fever duration (OR: 1.860; 95% CI: 1.429–2.421), leucocyte count (OR: 1.198; 95% CI: 1.061–1.354), lymphocyte proportion (OR: 0.958; 95% CI: 0.931–0.986), proportion of CD3+ T cells (OR: 0.929; 95% CI: 0.898–0.962), TNF-α (OR: 1.057; 95% CI: 1.026–1.089), and IL-10 (OR: 1.049; 95% CI: 1.026–1.073) were confirmed to be the independent risk factors for severe H1N1 infection in the post-COVID-19 group (Fig. 3a).