IL6 and Increased total leukocyte count: Severe cases exhibited marked leukocytosis (median 8.12 × 109 L−1, IQR 7.00–11.82 vs. 5.96 × 109 L−1, 4.18–8.53; p = 0.003) and an almost five-fold higher IL-6 concentration (18 pg mL−1, 6–25 vs. 4 pg mL−1, 2–7; p < 0.001).