{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,22]],"date-time":"2026-07-22T18:25:01Z","timestamp":1784744701875,"version":"3.55.0"},"reference-count":19,"publisher":"Public Library of Science (PLoS)","issue":"7","license":[{"start":{"date-parts":[[2026,7,22]],"date-time":"2026-07-22T00:00:00Z","timestamp":1784678400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/publicdomain\/zero\/1.0\/"}],"content-domain":{"domain":["www.plosone.org"],"crossmark-restriction":false},"short-container-title":["PLoS One"],"abstract":"\n Objective<\/jats:title>\n To characterize the epidemiological features of pertussis among pediatric patients tested by polymerase chain reaction (PCR) at a tertiary children's hospital in Chengdu from May 2024 to April 2025, with particular emphasis on temporal variation and age distribution, to inform regional prevention strategies.<\/jats:p>\n <\/jats:sec>\n \n Methods<\/jats:title>\n \n This retrospective cross-sectional study included 19,084 pediatric patients who underwent PCR testing for\n Bordetella pertussis<\/jats:italic>\n . Multivariable logistic regression and subgroup analyses were used to examine associations between PCR positivity and season, age group, sex, and visit type.\n <\/jats:p>\n <\/jats:sec>\n \n Results<\/jats:title>\n \n The overall PCR positivity rate was 20.47% (3,905\/19,084). Summer had the highest positivity rate (25.62%) and accounted for the majority of positive cases (67.12%, 2,621\/3,905), followed by spring (21.50%; 23.58% of cases, 921\/3,905). The monthly number of positive cases peaked in June 2024 (n\u2009=\u20091,078). School-aged children (6 to <12 years) represented the largest proportion of positive cases (56.72%, 2,215\/3,905) and had significantly higher PCR positivity than other age groups (\u03c7\u00b2\u2009=\u20091098.21, df\u2009=\u20094,\n P<\/jats:italic>\n \u2009<\u20090.001). In multivariable analysis, school-aged children had higher odds of PCR positivity than adolescents (adjusted OR = 1.55, 95% CI 1.23\u20131.95). No significant association with sex was observed. Outpatients showed higher PCR positivity than inpatients (21.41% vs. 13.66%; crude OR = 1.72, 95% CI 1.52\u20131.95,\n P<\/jats:italic>\n \u2009<\u20090.001). The outpatient advantage was most pronounced in spring (crude OR = 1.95) and summer (crude OR = 1.44), with a significant interaction by season (\n P<\/jats:italic>\n \u2009=\u20090.013).\n <\/jats:p>\n <\/jats:sec>\n \n Conclusion<\/jats:title>\n This hospital-based study identified a substantial burden of PCR-confirmed pertussis among symptomatic children in Chengdu during the study period, with a prominent peak from May to July 2024 and the highest positivity among school-aged children. These findings may partly reflect waning vaccine-induced immunity and increased social contact in school settings, and support strengthened surveillance, timely PCR testing, and targeted pertussis prevention strategies for school-aged children.<\/jats:p>\n <\/jats:sec>","DOI":"10.1371\/journal.pone.0351127","type":"journal-article","created":{"date-parts":[[2026,7,22]],"date-time":"2026-07-22T17:31:47Z","timestamp":1784741507000},"page":"e0351127","update-policy":"https:\/\/doi.org\/10.1371\/journal.pone.corrections_policy","source":"Crossref","is-referenced-by-count":0,"title":["The 2024\u20132025 Pertussis outbreak in children in Chengdu: A large-scale retrospective cross-sectional study"],"prefix":"10.1371","volume":"21","author":[{"given":"Xu","family":"Zhang","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0000-8968-6157","authenticated-orcid":true,"given":"Hongjia","family":"Chen","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"340","published-online":{"date-parts":[[2026,7,22]]},"reference":[{"issue":"12","key":"pone.0351127.ref001","doi-asserted-by":"crossref","first-page":"1346","DOI":"10.3390\/vaccines12121346","article-title":"Epidemiology of pertussis after the covid-19 pandemic: analysis of the factors involved in the resurgence of the disease in high-, middle-, and low-income countries","volume":"12","author":"LF Bricks","year":"2024","journal-title":"Vaccines (Basel)"},{"issue":"1","key":"pone.0351127.ref002","doi-asserted-by":"crossref","first-page":"2389086","DOI":"10.1080\/22221751.2024.2389086","article-title":"Rising pertussis cases and deaths in China: current trends and clinical solutions","volume":"13","author":"H Yahong","year":"2024","journal-title":"Emerg Microbes Infect"},{"issue":"1","key":"pone.0351127.ref003","doi-asserted-by":"crossref","first-page":"21197","DOI":"10.1038\/s41598-024-72165-w","article-title":"Assessing the impact of COVID-19 non-pharmaceutical interventions and relaxation policies on Class B respiratory infectious diseases transmission in China","volume":"14","author":"N Wu","year":"2024","journal-title":"Sci Rep"},{"issue":"23","key":"pone.0351127.ref004","doi-asserted-by":"crossref","first-page":"2400301","DOI":"10.2807\/1560-7917.ES.2024.29.23.2400301","article-title":"Pertussis outbreak in neonates and young infants across Italy, January to May 2024: implications for vaccination strategies","volume":"29","author":"M Poeta","year":"2024","journal-title":"Euro Surveill"},{"issue":"19","key":"pone.0351127.ref005","doi-asserted-by":"crossref","first-page":"9607","DOI":"10.3390\/ijms26199607","article-title":"Pertussis-A re-emerging threat despite immunization: an analysis of vaccine effectiveness and antibiotic resistance","volume":"26","author":"A Duda-Madej","year":"2025","journal-title":"Int J Mol Sci"},{"issue":"23","key":"pone.0351127.ref006","doi-asserted-by":"crossref","first-page":"3120","DOI":"10.1016\/j.vaccine.2021.04.032","article-title":"Pertussis vaccine effectiveness and duration of protection - 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