[Clinical characteristics of pertussis in hospitalized children under 3 months].

Demographic data and clinical data were collected retrospectively from patients with pertussis at the Children's Hospital Affiliated to the Capital Institute of Pediatrics between March 2011 and February 2023. Among the 270 hospitalized patients, 151 cases were male and 119 were female. The youngest age of admission was 10 days and the eldest age of admission was 11 years. The 270 hospitalized patients were divided into two groups according to onset age: <3 months (n=143) and≥3 months (n=127). For those in the <3-month-old group, the incidence of severe pneumonia and severe pertussis were 21.0% and 38.5%, respectively, both were significantly higher than those in≥3-month-old group (7.9% and 11.0%, both P<0.05). For those in the <3-month-old group, paroxysmal spasmodic cough, post-tussive vomiting, paroxysmal cyanosis, apnea, and decreased heart rate after coughing were 86.7%, 25.2%, 38.5%, 7.0% and 16.8%, respectively, all were significantly higher than those in ≥3-month-old group (76.4%, 10.2%, 15.7%, 1.6% and 1.6%, all P<0.05). For those in the<3-month-old group, the incidence of hypoxemia, respiratory failure, were 36.4%, 16.8%, respectively, and both were significantly higher than those in≥3-month-old group (10.2%, 7.1%, P<0.05). It indicated that among the infants under 3 months, the incidence of vomiting after coughing, paroxysmal cyanosis, apnea, hypoxemia, respiratory failure, decreased heart rate after coughing and severe pneumonia were significantly higher than those above 3 months. Infants under 3 months were prone to severe pertussis.