This study showed that CRP increased significantly at the initial stage of severe COVID‐19 infections, before CT findings and predicted a severe case early on.

In this cohort study, 27 consecutive patients with COVID‐19 and 75 patients with influenza were retrospectively enrolled.

The levels of C‐reactive protein (CRP) in severely affected patients were higher than those in the mild group at the initial and progression stages. Correlation analysis showed that CRP , erythrocyte sedimentation rate, and granulocyte/lymphocyte ratio were positively associated with CT severity scores.

The receiver-operating characteristic analysis found that area under the curve for CRP on the first visit for predicting severe COVID‐19 was 0.87 at a vutoff of 20.42 mg/L, and sensitivity and specificity were 83% and 91%, respectively.