{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,28]],"date-time":"2026-08-28T17:36:21Z","timestamp":1787938581388,"version":"build-2784847793"},"reference-count":34,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,3,11]],"date-time":"2026-03-11T00:00:00Z","timestamp":1773187200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Public Health"],"abstract":"\n Background<\/jats:title>\n \n Chlamydia pneumoniae<\/jats:italic>\n is a common pathogen involved in acute respiratory tract infections (ARTIs) in children.\n <\/jats:p>\n <\/jats:sec>\n \n Methods<\/jats:title>\n \n Children with ARTIs attending the West China Second Hospital of Sichuan University from January 2022 to December 2023 were selected. IgM antibodies against Chlamydia pneumoniae (\n C. pneumoniae<\/jats:italic>\n ) were detected using a chemiluminescence immunoassay. Demographic and temporal differences in IgM positivity were compared between 2022 and 2023.\n <\/jats:p>\n <\/jats:sec>\n \n Results<\/jats:title>\n \n Over the two-year period, 20,689 children were included. In 2022, under stringent COVID-19 non-pharmaceutical interventions (NPIs), 453 positive and 10,092 negative cases, with IgM seropositivity rate of 4.3%. In 2023, following the nationwide relaxation of these NPIs, 602 positive cases, and 9,542 negative cases for IgM seropositivity rate of 5.9%, which was significantly higher than that in 2022 (\n P<\/jats:italic>\n &lt; 0.001). The IgM seropositivity rate of\n C. pneumoniae<\/jats:italic>\n infection in children aged 3 to 14 years was significantly higher in 2023 than in 2022 (\n P<\/jats:italic>\n &lt; 0.05). The IgM seropositivity rate from January to May 2023 was significantly higher than that during the same period of 2022 (\n P<\/jats:italic>\n &lt; 0.001), while the IgM seropositivity rate from July to October 2023 was significantly lower than that during the same period in 2022 (\n P<\/jats:italic>\n &lt; 0.05). The IgM seropositivity rate in females aged 3 to 6 years was significantly higher than that of males in the same age group (\n P<\/jats:italic>\n &lt; 0.05). With the exception of 0- to 1-year-olds, the IgM seropositivity rates of females were significantly higher than those of males in the same age groups in 2023 (\n P<\/jats:italic>\n &lt; 0.05). Moreover, the IgM seropositivity rate of females was significantly higher than that of males in March, June, and September in 2022 (\n P<\/jats:italic>\n &lt; 0.05), and the IgM seropositivity rate of females was significantly higher than that of males in the same period in January, May, October, and November in 2023 (\n P<\/jats:italic>\n &lt; 0.05).\n <\/jats:p>\n <\/jats:sec>\n \n Conclusion<\/jats:title>\n \n The results revealed that the epidemic trend and population susceptible to\n C. pneumoniae<\/jats:italic>\n changed from 2022 to 2023, providing valuable insights into the prevention, diagnosis and management of\n C. pneumoniae<\/jats:italic>\n infection in this region.\n <\/jats:p>\n <\/jats:sec>","DOI":"10.3389\/fpubh.2026.1729558","type":"journal-article","created":{"date-parts":[[2026,3,11]],"date-time":"2026-03-11T14:10:50Z","timestamp":1773238250000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":2,"title":["Epidemiology of Chlamydia pneumoniae infection in children with acute respiratory tract infections, Chengdu, 2022\u20132023"],"prefix":"10.3389","volume":"14","author":[{"given":"Yifei","family":"Duan","sequence":"first","affiliation":[{"name":"Department of Laboratory Medicine, West China Second University Hospital, Sichuan University .","place":["Chengdu, Sichuan, China"]},{"name":"Key Laboratory of Birth Defects and Related Diseases of Women and Children, Sichuan University, Ministry of Education","place":["Chengdu, Sichuan, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yu","family":"Wu","sequence":"additional","affiliation":[{"name":"Department of Laboratory 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