The correlations of CIRP with minor criteria and SOFA and PSI scores were stronger than those of PCT, IL-6 and CRP, respectively, and CIRP was also strongly associated with PCT, IL-6 and CRP, indicating that CIRP might determine the severity of CAP and the presences of minor criteria and suggesting that CIRP might be a novel and intriguing biomarker for pneumonia to monitor host response. Here, IL6 is linked to susceptibility to pneumonia measurement.