{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,11,19]],"date-time":"2025-11-19T11:39:07Z","timestamp":1763552347935,"version":"3.41.0"},"reference-count":30,"publisher":"Public Library of Science (PLoS)","issue":"6","license":[{"start":{"date-parts":[[2025,6,5]],"date-time":"2025-06-05T00:00:00Z","timestamp":1749081600000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Korea Disease Control and Prevention Agency\u2019s research and development project","award":["2022-ER1903-01"],"award-info":[{"award-number":["2022-ER1903-01"]}]}],"content-domain":{"domain":["www.plosone.org"],"crossmark-restriction":false},"short-container-title":["PLoS One"],"abstract":"<jats:sec id=\"sec017\">\n<jats:title>Background<\/jats:title>\n<jats:p>During the COVID-19 endemic phase, pulmonary sequelae substantially contributed to disease burden. Immunologic responses may be critical in both acute COVID-19 and in long-term sequelae. We aimed to evaluate associations between convalescent neutralizing antibodies and long-term pulmonary sequelae in patients hospitalized with mild to moderate COVID-19.<\/jats:p>\n<\/jats:sec>\n<jats:sec id=\"sec018\">\n<jats:title>Methods<\/jats:title>\n<jats:p>Among patients who recovered from hospitalization due to COVID-19, those who consented to participate in the study provided convalescent serum between June 2021 and April 2022. These baseline patients were invited for a second follow-up visit between September and November 2023. A serum sample was collected at the second visit, and low-dose chest computed tomography (CT) was performed. Pulmonary sequelae were defined as findings of fibrotic, fibrotic-like, and ground-glass opacities (GGOs). Antibody and cytokine levels were assessed in serum samples from the baseline convalescent phase, and antibody levels were also measured in the serum sample at the second visit.<\/jats:p>\n<\/jats:sec>\n<jats:sec id=\"sec019\">\n<jats:title>Results<\/jats:title>\n<jats:p>A total of 107 patients were enrolled at baseline, and 37 consented to the second follow-up visit. Most second-visit patients (97.3%, 36\/37) did not require an oxygen supply beyond that provided via masks or nasal prongs. Twenty-two patients (59.5%) exhibited pulmonary sequelae on chest CT at a median follow-up period of 27 months (interquartile range 25\u201328, range 22\u221230) after hospitalization for COVID-19. Fifteen patients (40.5%) had fibrotic or fibrotic-like pulmonary changes, and twelve (32.4%) had GGOs. Pulmonary sequelae were associated with older age (adjusted odds ratio 1.130, 95% confidence interval 1.028\u20131.243; P\u2009=\u20090.011). There were no significant differences in convalescent cytokines or neutralizing antibodies between patients with pulmonary sequelae and those without.<\/jats:p>\n<\/jats:sec>\n<jats:sec id=\"sec020\">\n<jats:title>Conclusion<\/jats:title>\n<jats:p>Pulmonary sequelae were quite common on chest CT after two years of mild to moderate COVID-19 and were associated with older age. The immunological or inflammatory status in the immediate post-acute infection period did not predict long-term complications.<\/jats:p>\n<\/jats:sec>","DOI":"10.1371\/journal.pone.0325379","type":"journal-article","created":{"date-parts":[[2025,6,5]],"date-time":"2025-06-05T17:57:27Z","timestamp":1749146247000},"page":"e0325379","update-policy":"https:\/\/doi.org\/10.1371\/journal.pone.corrections_policy","source":"Crossref","is-referenced-by-count":1,"title":["Long-term pulmonary sequelae and convalescent immune reactions in mild to moderate COVID-19 patients during the active treatment era"],"prefix":"10.1371","volume":"20","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-9039-8328","authenticated-orcid":true,"given":"Minkyeong","family":"Lee","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Byoung 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