Compared to white cell counts and procalcitonin level, the C-reactive protein level had the best diagnostic accuracy for documented infections, with an AUC of 0.822 and 95%CI 0.756–0.887 in the overall cohort of patients and an AUC of 0.720 and 95%CI 0.633–0.808 for patients diagnosed with COVID-19 pneumonia. The gene discussed is CRP; the disease is infection.