C-reactive protein (CRP) and ferritin levels were higher in patients with COVID-19 than in those without (CRP: median [range], 18.73 [0.09-50.35] mg/dL vs 9.53 [0.03-30.0] mg/dL; P < .001 [to convert to milligrams per liter, multiply by 10]; ferritin: median [range], 1028 [22.6-53 315] ng/mL vs 471.8 [8.8-8863] ng/mL; P = .01 [to convert to micrograms per liter, multiply by 1.0]). Here, CRP is linked to COVID-19.