Clinical epidemiological characteristics and risk factors for severe pertussis in children in Xiamen

Over the past few years, no pertussis outbreaks or significant increases in case numbers have been documented in Xiamen, and related academic research remains scarce. To address this knowledge gap, this study conducted a retrospective analysis of the epidemiological characteristics of pediatric pertussis in Xiamen in 2024, as well as the clinical features and risk factors for severe cases, This work aims to provide empirical evidence for optimizing local pertussis prevention and control strategies and clinical case management.

Epidemiological characteristics were analyzed by collecting demographic information on all confirmed pertussis cases admitted to Xiamen Children's Hospital from January to December 2024 through the hospital's infectious disease reporting system. Clinical data for hospitalized patients were extracted from electronic medical records to identify risk factors associated with severe pertussis. During outbreak periods, nasopharyngeal swab specimens were collected from selected hospitalized patients and their caregivers for real-time polymerase chain reaction (PCR) detection. A subset of these specimens was subjected to Bordetella pertussis culture, and the isolated strains were further subjected to antimicrobial susceptibility.

A total of 287 confirmed pertussis cases were reported in 2024. The median age of the patients was 5.00 years (interquartile range [IQR]: 0.33-7.00 years), with children aged 6 years and older accounting for 45.30%(130/287). Among all cases, 126 (43.90%) were hospitalized, with a median age of 0.46 years (IQR: 0.17-5.00 years), and 17 (13.49%) of these hospitalized cases were classified as severe, with a median age of 0.08 years (IQR: 0.08-0.21 years). Among the 126 hospitalized cases, 51 (40.48%) had possible household exposure; 89(71.43%) presented with paroxysmal coughing; 31(25.40%) experienced post-tussive emesis and 16 (12.70%) had inspiratory whoop; 68 (53.97%) manifested cyanosis or facial flushing during coughing and 4 (3.17%) had apnea; 28 (22.22%) had fever. A total of 58 cases (46.03%) had no documented pertussis vaccination history. Multivariate logistic regression analysis identified unvaccinated status and elevated white blood cell count (> 20 × 10⁹/L), as independent risk factors for severe pertussis. In vitro drug susceptibility testing of 25 Bordetella pertussis isolates demonstrated high-level resistance to azithromycin but sensitivity to trimethoprim-sulfamethoxazole, levofloxacin, doxycycline, ceftazidime and cefoperazone/sulbactam.

During the 2024 pertussis epidemic in Xiamen, school-age children aged 6 years and older constituted the most affected population. However, severe pertussis occurred predominantly in unvaccinated infants under 6 months of age. Therefore, timely completion of the primary pertussis vaccination series in infants remains a key strategy for preventing severe pertussis. Additionally, supplementary vaccination for school-age children is necessary to boost waning immunity. Macrolide antibiotics is not advised for empirical treatment of pertussis in China.

Not applicable.