Objective To understand the detection rates of different pneumonia pathogens in children < 5 years in China′s mainland from 2014 to 2023 and provide a basis for the development of preventive and control measures related to childhood pneumonia in China.

Methods We searched China National Knowledge Infrastructure (CNKI), Wanfang Data, VIP, SinoMed, PubMed, Embase, and Web of Science with the time interval from January 1, 2014 to October 10, 2024 for the articles about the detection of different pneumonia pathogens in children < 5 years in China′s mainland. Stata 18.0 was used for meta-analysis of the included articles.

Results A total of 65 articles (55 in Chinese and 10 in English) involving 197 146 patients were included. The meta-analysis revealed that from 2014 to 2023 in China′s mainland, the overall detection rate of bacterial pathogens causing pneumonia in children < 5 years was 50.9% (95%CI: 41.8%–60.0%), with Streptococcus pneumoniae having the highest detection rate of 14.8% (95%CI: 12.4%–17.1%). The overall detection rate of viral pathogens was 47.8% (95%CI: 37.8%–57.8%), with respiratory syncytial virus (RSV) having the highest detection rate of 21.8% (95%CI: 18.3%–25.2%). The overall detection rate of Mycoplasma and Chlamydia was 18.0% (95%CI: 14.9%–21.1%), with Mycoplasma having the highest detection rate of 16.5% (95%CI: 13.3%–19.7%). Subgroup analysis revealed that the detection rates of bacterial pathogens among children in the < 1-year group, 1–< 3-year group, 3–< 5-year group, and ungrouped < 5-year children were 49.2%, 49.4%, 75.0%, and 43.6%, respectively. In eastern and central-western China, the detection rates of bacterial pathogens in children < 5 years were 38.9% and 54.6%, respectively. During 2014–2019 and 2020–2023, the detection rates of bacterial pathogens in children < 5 years were 53.7% and 31.5%, respectively. The detection rates of bacterial pathogens varied across different ages, regions, and time periods (all P < 0.001). The detection rates of viral pathogens among children in the < 1-year group, 1–< 3-year group, 3–< 5-year group, and ungrouped < 5-year children were 53.5%, 48.3%, 62.0%, and 38.7%, respectively. In eastern and central-western China, the detection rates of viral pathogens in children < 5 years were 47.0% and 42.8%, respectively. During 2014–2019 and 2020–2023, the detection rates of viral pathogens in children < 5 years were 47.1% and 51.2%, respectively. The detection rates of viral pathogens varied across different ages, regions, and time periods (all P < 0.001). The detection rates of Mycoplasma and Chlamydia among children in the < 1-year group, 1–< 3-year group, 3–< 5-year group, and ungrouped < 5-year children were 10.1%, 25.1%, 27.6%, and 20.7%, respectively. In eastern and central-western China, the detection rates of Mycoplasma and Chlamydia in children < 5 years were 18.2% and 16.5%, respectively. During 2014–2019 and 2020–2023, the detection rates of Mycoplasma and Chlamydia in children < 5 years were 18.7% and 19.3%, respectively. The detection rates of Mycoplasma and Chlamydia varied across different ages, regions, and time periods (all P < 0.001).

Conclusion From 2014 to 2023 in China′s mainland, bacterial pathogens causing pneumonia showed the highest detection rates among children < 5 years, with S. pneumoniae being the predominant bacterial pathogen. Children in the 3–< 5-year group showed elevated detection rates across all pathogen types. Regional and temporal variations were significant: bacterial infections dominated in central-western China and during 2014–2019, whereas eastern China and the 2020–2023 period were characterized by higher rates of viral infections and Mycoplasma and Chlamydia infections.