# Multi-dimensional epidemiology of pediatric acute respiratory tract infection in Ningbo, China (2020–2024): age-specific susceptibility, pathogen dynamics, and epidemiological trends

## TL;DR

This study analyzes pediatric respiratory infections in Ningbo, China, from 2020 to 2024, revealing age-specific patterns, pathogen dynamics, and co-infection trends.

## Contribution

The study provides a systematic multi-pathogen analysis of pediatric ARTI in Ningbo, including age-specific susceptibility and co-infection rates.

## Key findings

- ARTI cases peaked in 2023, with highest incidence in autumn and lowest in summer.
- Children aged 6 years showed highest susceptibility to acute lower respiratory infections.
- Co-infection rates reached 39.49% when combining viral and bacterial testing.

## Abstract

Pediatric acute respiratory tract infection (ARTI) constitutes a major global health threat. Since 2020, global containment measures have disrupted pathogen circulation patterns, leading to altered epidemiological profiles across multiple pathogens with marked regional heterogeneity. Current research in Ningbo predominantly focuses on single-pathogen surveillance or short-term monitoring, lacking systematic analysis of multi-pathogen interactive dynamics, age-specific susceptibility mechanisms, and co-infections.

Clinical data from all 191,967 pediatric patients with ARTI at Ningbo LiHuili Hospital (2020–2024) were collected. Laboratory testing including influenza A/B virus (IFV-A/B) detection, Mycoplasma pneumoniae (MP) testing, 13 respiratory pathogens analysis, and bacterial culture was systematically integrated and analyzed.

From 2020 and 2024, the number of ARTI cases initially increased and then decreased, peaking in 2023. The incidence was highest in autumn and lowest in summer. Among all cases, 75,001 (39.07%) were diagnosed with acute lower respiratory infection (ALRI), with children aged 6 years exhibiting the highest susceptibility. Of the 41,766 cases tested, the overall pathogen detection rate was 67.61%. IFV-A/B, Human Parainfluenza Virus (HPIV), and Human Adenovirus (HAdV) were more frequently detected in acute upper respiratory tract infections (AURI) (P < 0.05), while Human Rhinovirus (HRV), Respiratory Syncytial Virus (RSV), and MP were predominantly identified in ALRI cases (P < 0.05). Each pathogen exhibited age-specific susceptibility patterns. Several pathogens, such as IFV-A, MP, and HAdV, displayed distinctive epidemic peaks. Co-infections were common, with a 17.38% co-infection rate observed in the group tested for 13 respiratory pathogens, and a higher co-infection rate of 39.49% when testing combined respiratory pathogens and bacteria. Correlation analysis among pathogens revealed predominant antagonistic interactions between viruses, positive associations among bacteria, and generally positive interactions between viruses and bacteria, though overall correlation strengths were weak.

Pediatric ARTI exhibit age-specific susceptibility and pathogen variation. The 2023–2024 resurgence demands precision control strategies for optimized intervention.