Specifically, compared to the pre-COVID-19 group, the post-COVID-19 group revealed markedly longer duration of fever (4.0 vs. 3.0 days, P < 0.001), higher fever peak (39.0 vs. 38.8 °C, P < 0.001), more frequent cough (90.7% vs. 82.5%, P = 0.003) and seizures (18.2% vs. 7.6%, P < 0.001), as well as higher levels of CRP (14.9 vs. 11.7 mg/L, P < 0.001), IL-6 (20.5 vs. 11.0 pg/mL, P < 0.001), IL-10 (16.5 vs. 14.9 pg/mL, P = 0.03), CK-MB (44.9 vs. 36.0 U/L, P < 0.001) and fibrinogen (3.9 vs. 3.7 g/L, P = 0.046). This evidence concerns the gene IL6 and COVID-19.