Objective  To compare the clinical manifestations of pertussis in children of different ages and different immunization statuses in Wenzhou, and to explore the limitations of diagnostic criteria for pertussis.

  Methods  The clinical data of 288 children diagnosed with pertussis at Yuying Children’s Hospital & the Second Affiliated Hospital of Wenzhou Medical University from October 2017 to December 2019 were retrospectively analyzed. The clinical characteristics of children of different ages and different immunization statuses were analyzed. Their clinical data were compared to relevant diagnostic criteria of pertussis in children of different ages according to the Recommendations for Diagnosis and Treatment of Chinese Children with Pertussis and the diagnosis conformity rate was analyzed.

  Results   Among the 288 children, 124 cases (43.06%) were 3 months old or younger, and 164 cases (288, 56.94%) were >3 months old. Among patients≤3 months of age, cyanosis, three-depression sign, face redness, dyspnea and peripheral blood lymphocyte ratio were significantly higher than those of patients >3 months of age. They also had higher incidence of pneumonia, higher proportion of developing severe pertussis, and longer stay at the hospital. All these findings showed statistically significant difference (P<0.05). 83 children were fully immunized (receiving the full course of vaccination), and 205 were not fully immunized (not receiving the full course of vaccination or being unvaccinated). The proportion of children presenting cyanosis, shortness of breath, three depression sign and face redness in the incomplete immunization group was higher than that in the complete immunization group. In the incomplete immunization group, the proportion of lymphocytes was higher, the level of C-reactive protein (CRP) was lower, and the length of hospitalization was longer than those of the complete immunization group. All the differences were statistically significant (P<0.05). Among patients aged ≤3 months, the conformity rate of diagnosis (112/114, 90.32%) upon admission was higher than that among patients aged >3 months (119/164, 72.56%). Among patients aged ≤3 months, 41.94% (52/124, while 54.03% (67/124) of the patients aged ≤3 months had WBC count <20×10⁹ L⁻¹.

  Conclusion  Pertussis in children ≤3 months of age in Wenzhou City were more serious, showing higher rate of diagnosis conforming to the recommended clinical diagnostic criteria than that in children >3 months old. The WBC threshold in routine blood test of ≤3 months old could be lowered appropriately and the current diagnostic criteria still needed improvement.