{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,7]],"date-time":"2026-07-07T09:17:18Z","timestamp":1783415838404,"version":"3.54.6"},"reference-count":17,"publisher":"PeerJ","license":[{"start":{"date-parts":[[2026,7,7]],"date-time":"2026-07-07T00:00:00Z","timestamp":1783382400000},"content-version":"unspecified","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100004775","name":"Natural Science Foundation of Gansu Province","doi-asserted-by":"crossref","award":["24JRRE013"],"award-info":[{"award-number":["24JRRE013"]}],"id":[{"id":"10.13039\/501100004775","id-type":"DOI","asserted-by":"crossref"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"abstract":"<jats:sec>\n                    <jats:title>Objective<\/jats:title>\n                    <jats:p>To assess the impact of the COVID-19 pandemic and associated containment measures on the development of the immune system in children.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>This retrospective study analyzed clinical data from children aged 0\u201313 years diagnosed with respiratory tract infections at Tianshui First People\u2019s Hospital between 2019 and 2024. The dataset included 79,703 complete blood count samples and 7,931 immunoglobulin (IgG, IgA, IgM) analysis samples. Non-parametric tests (rank-sum test) and generalized linear models (Gamma distribution with Log link function) were employed for statistical analysis to evaluate the effects of different years, age groups, genders, and diagnostic types (upper\/lower respiratory tract infections) on immunological parameters.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>The study found that the COVID-19 pandemic had heterogeneous effects on various immune cell types. Neutrophil and monocyte counts showed an increasing trend during the pandemic, whereas lymphocyte, eosinophil, and basophil counts were suppressed\u2014with lymphocyte reduction being particularly pronounced. The suppressive effect on basophils may be persistent. Compared with 2019, no significant changes were observed in immunoglobulin levels among children from 2020 to 2022. However, beginning in 2023, serum concentrations of immunoglobulin G and immunoglobulin M showed a marked increase. This upward trend persisted through 2024, accompanied by a concurrent rebound in lymphocyte counts. Further analysis of interaction effects among age, gender, and diagnosis revealed that the impact of the pandemic on immune development was also significantly influenced by these factors.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>The COVID-19 pandemic and associated public health interventions have altered children\u2019s patterns of pathogen exposure, delayed the development of adaptive immunity, and disrupted the balance between innate and adaptive immunity, thereby exerting complex and long-lasting effects on immune system maturation. These findings provide valuable data for understanding the response patterns of the children\u2019s immune system under exceptional public health events and offer guidance for formulating targeted child health policies, vaccination strategies, and clinical practices in the future.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.7717\/peerj.21469","type":"journal-article","created":{"date-parts":[[2026,7,7]],"date-time":"2026-07-07T08:38:33Z","timestamp":1783413513000},"page":"e21469","source":"Crossref","is-referenced-by-count":0,"title":["The impact of COVID-19 social isolation and reduced microbial exposure on the immune system in children: a retrospective study"],"prefix":"10.7717","volume":"14","author":[{"given":"Xuan","family":"Wu","sequence":"first","affiliation":[{"name":"Precision Medicine Laboratory, The Tianshui First People\u2019s Hospital, Tianshui, Gansu, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Shiwei","family":"Li","sequence":"additional","affiliation":[{"name":"Precision Medicine Laboratory, The Tianshui First People\u2019s Hospital, Tianshui, Gansu, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yahong","family":"Li","sequence":"additional","affiliation":[{"name":"Precision Medicine Laboratory, The Tianshui First People\u2019s Hospital, Tianshui, Gansu, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Dongxia","family":"Shi","sequence":"additional","affiliation":[{"name":"Precision Medicine Laboratory, The Tianshui First People\u2019s Hospital, Tianshui, Gansu, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ping","family":"Chen","sequence":"additional","affiliation":[{"name":"Geriatrics Department, Tianshui First People\u2019s Hospital, Tianshui, Gansu, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"4443","published-online":{"date-parts":[[2026,7,7]]},"reference":[{"key":"10.7717\/peerj.21469\/ref-1","doi-asserted-by":"publisher","first-page":"e865","DOI":"10.52225\/narra.v4i2.865","article-title":"Determinants of COVID-19 severity and mortality in children: a retrospective and multicenter cohort study in Medan, Indonesia","volume":"4","author":"Airlangga","year":"2024","journal-title":"Narra J"},{"key":"10.7717\/peerj.21469\/ref-2","doi-asserted-by":"publisher","first-page":"2000749","DOI":"10.1183\/13993003.00749-2020","article-title":"Will children reveal their secret? 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