CRP and COVID-19: Although the oxygenation index was normal in patients with subsequently critical COVID-19, CRP (41.5 [12.853–69.7] mg/L, reference: <10.00 mg/L) and D-dimer (1170.0 [640.0–1525.0] μg/L, reference: <500.0 μg/L) levels, leukocyte and neutrophil counts, and NLR (6.3 [3.1–21.1], reference: <3.2) were significantly higher in these patients than in those with moderate COVID-19.