To investigate the clinical characteristics of pediatric patients with pertussis across different age groups.

Clinical data of 567 pediatric patients with pertussis diagnosed at Chengdu Public Health Clinical Medical Center from January 2022 to December 2024 were analyzed, retrospectively. Patients were grouped into≤3 months group (118 cases), 3-36 months group (180 cases), 36 months-6 years old group (115 cases) and>6 years old group (154 cases). General information, vaccination history, epidemiological characteristics, clinical manifestations, and laboratory test results [white blood cell (WBC) count, absolute lymphocyte count (ALC) and platelet (PLT) count] were collected, respectively. Intergroup comparisons were performed by Chi-square test or Kruskal-Wallis H test.

Among the 567 enrolled children, the incidence rates were higher in 36 month-6 years old [20.3% (115/567)] and>6 years old groups [27.2% (154/567)] , respectively; Cases occurred throughout the year, with a peak incidence in summer (61.2%, 347/567), followed by spring (22.4%, 127/567); while 262 children (46.2%) were unvaccinated or not fully immunized. The main clinical symptoms included paroxysmal spasmodic cough (84.7%, 480/567), vomiting (35.8%, 203/567) and crowing-like stridor (29.6%, 168/567). The incidence of paroxysmal spasmodic cough (χ²=38.36, P<0.001), crowing stridor (χ²=47.44, P<0.001), wet rales or wheezing (χ²=92.22, P<0.001) and pneumonia (χ²=47.49, P<0.001) were significantly different among children with pertussis of all age groups; moreover, the incidence decreases with age increasing in pediatric patients, both≤3 month old group and 3-36 month old group exhibiting significantly higher rates of these clinical manifestations compared with>6 years old group (all P<0.001). White blood cell (WBC) count (H=68.65, P<0.001), absolute lymphocyte count (ALC) (H=163.25, P<0.001) and platelet (PLT) count (H=190.72, P<0.001) were significantly different among children with pertussis of all age groups; the above mentioned indicators were significantly higher in≤3 month old group and 3-36 month-old group compared with 36 month to 6 years old group and>6 years old group, all with significant differences (all P<0.001).

Clinical manifestations of pertussis in young children are typical, particularly evident in infants aged≤3 months. WBC, ALC and PLT levels are generally elevated in young pediatric patients, which provides valuable reference for early diagnosis of pertussis when combined with clinical presentations.