CRP and bacterial infectious disease: In patients without secondary infection, both PCT and CRP decreased over time (Fig. 1a), with PCT values lower (peak geometric mean [95% CI] of 0.64 [0.32–1.27] μg/L) than CRP (peak geometric mean [95% CI] of 192 [107–342] mg/L) compared to their respective cutoff values for bacterial infection (< 0.5 μg/L and < 100 mg/L, respectively).