To investigate the distribution characteristics of pathogens in children with respiratory tract infection in Nanjing and surrounding areas in 2024.

The clinical data of pediatric patients (≤18 years old) who underwent nucleic acid testing for 11 respiratory pathogens due to upper respiratory tract infection or complicated with upper respiratory tract infection at Nanjing Children’s Hospital affiliated to Nanjing Medical University from January to December 2024 were analyzed, retrospectively. Total of 5 973 clinical samples were collected, and the positive detection rates of 11 respiratory pathogens were analyzed by Chi-square test based on different genders, ages and specific periods (such as winter and summer vacations, as well as spring and autumn semesters).

The top five pathogens ranked by detection rate were: human rhinovirus (HRV) (1 150 cases, 31.27%), Mycoplasma pneumoniae (957 cases, 26.01%), adenovirus (672 cases, 18.27%), parainfluenza virus (525 cases, 14.27%) and respiratory syncytial virus (349 cases, 9.49%). The highest positive detection rates were observed in 1 to 3-year-old child group (68.9%) and during winter vacation (73.7%). Statistically significant differences in respiratory pathogen distribution were noted across different age groups (χ²=140.393, P<0.001) and different semesters and holidays (χ²=21.648, P<0.001). The positive rates of HRV (25.7%), parainfluenza virus (15.2%), adenovirus (17.0%) and Mycoplasma pneumoniae (22.7%) were high and peaked between May and July. The prevalence of paramyxovirus, respiratory syncytial virus (RSV), influenza A virus and its H1N1 subtype began to rise from November to December. In contrast, the positive rate of influenza B virus gradually declined after the peak infection in January, showing a fluctuating trend with the gradual increase of influenza A virus. Mixed infections were not uncommon (accounting for 13.93% of the total samples), with two-virus mixed infection being the most (12.47% of the total samples). HRV (367/745, 49.26%) and Mycoplasma pneumoniae (238/745, 31.95%) exhibited the highest proportions of mixed infections.

During 2024, HRV accounted for the highest proportion of positive cases among pediatric respiratory pathogen infection in Nanjing and surrounding areas, with mixed infections commonly involving HRV and Mycoplasma pneumoniae. Infections were more prevalent in children aged 1-3 years old, necessitating enhanced infant protection and parental health education. The winter vacation and spring semester represent peak periods for high incidence of respiratory tract infections, during which child health protection and pathogen surveillance should be strengthened.