{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,20]],"date-time":"2026-07-20T02:29:18Z","timestamp":1784514558644,"version":"3.55.0"},"reference-count":44,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2026,1,15]],"date-time":"2026-01-15T00:00:00Z","timestamp":1768435200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["JCM"],"abstract":"<jats:p>Background: Post-COVID-19 syndrome (PCS) is defined as the persistence or development of new symptoms 3 months after the initial infection with the SARS-CoV-2 virus, these clinical aspects being most often associated with functional respiratory changes, as well as imagistic modifications. This study aimed to evaluate longitudinal changes in pulmonary function among patients with PCS, in relation to the severity of the acute COVID-19 episode and the time elapsed since infection. Methods: A retrospective, observational study was conducted at the Clinical Hospital of Pulmonary Diseases Ia\u0219i, Romania, between January 2021 and December 2022, including 97 adult patients with confirmed PCS. Demographic, clinical, and functional data were collected from medical records. Pulmonary function tests (PFTs) were performed according to ATS\/ERS standards, assessing Forced Vital Capacity (FVC), Forced Expiratory Volume in the First Second (FEV1), FEV1\/FVC ratio (Tiffeneau Index), Maximal Expiratory Flow at 50% and 25% of FVC (MEF50, MEF25), Diffusing Capacity of the Lung for Carbon Monoxide (adjusted for haemoglobin) (DLCO), Carbon Monoxide Transfer Coefficient (KCO), Alveolar Volume (AV), Total Lung Capacity (TLC) and Residual Volume (RV). Patients were grouped by time elapsed since infection (1\u20133, 4\u20137, 9\u201312, and up to 22 months). Statistical analyses included the Mann\u2013Whitney U test, Spearman\u2019s correlation, ROC curve analysis, and Principal Component Analysis (PCA). Results: A progressive improvement in FVC was observed up to 9\u201318 months post-infection (p &lt; 0.05), while FEV1 remained stable, suggesting a predominantly restrictive ventilatory pattern. Patients with moderate acute COVID-19 presented significantly lower FVC%, FEV1%, DLCO%, and KCO% values compared with those with mild disease (p &lt; 0.05). Diffusion abnormalities (DLCO and KCO) persisted beyond 12 months, indicating lasting alveolar-capillary impairment. ROC analysis identified TLC (AUC = 0.857), AV (AUC = 0.855), and KCO (AUC = 0.805) as the most discriminative parameters for residual dysfunction. PCA revealed three major functional domains\u2014airflow limitation, diffusion capacity, and lung volume\u2014explaining up to 70% of total variance. Conclusions: We are facing the emergence of a new phenomenon, namely a secondary post-COVID-19 pandemic of patients confronting with persistent post-COVID-19 symptoms who present with functional respiratory changes and who require careful monitoring in dynamics, personalized treatments and a multidisciplinary approach.<\/jats:p>","DOI":"10.3390\/jcm15020717","type":"journal-article","created":{"date-parts":[[2026,1,15]],"date-time":"2026-01-15T14:35:38Z","timestamp":1768487738000},"page":"717","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Impact of COVID-19 on Respiratory Function: A Post-Recovery Comparative Assessment"],"prefix":"10.3390","volume":"15","author":[{"given":"Daniela Robu","family":"Popa","sequence":"first","affiliation":[{"name":"\u201cGrigore T. Popa\u201d University of Medicine and Pharmacy, 700115 Iasi, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0002-9439-0590","authenticated-orcid":false,"given":"Corina","family":"Marginean","sequence":"additional","affiliation":[{"name":"Oncology and Palliative Care Department, \u201cGeorge Emil Palade\u201d University of Medicine and Pharmacy, Science and Technology of T\u00e2rgu Mure\u0219, 540142 T\u00e2rgu Mure\u0219, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mona Elisabeta","family":"Dobrin","sequence":"additional","affiliation":[{"name":"Biochemistry Department, Clinical Hospital of Pulmonary Diseases, 700116 Iasi, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3732-0350","authenticated-orcid":false,"given":"Radu Adrian","family":"Crisan Dabija","sequence":"additional","affiliation":[{"name":"\u201cGrigore T. Popa\u201d University of Medicine and Pharmacy, 700115 Iasi, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Oana-Elena","family":"Melinte","sequence":"additional","affiliation":[{"name":"\u201cGrigore T. Popa\u201d University of Medicine and Pharmacy, 700115 Iasi, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0000-0292-2453","authenticated-orcid":false,"given":"Stefan","family":"Dumitrache-Rujinski","sequence":"additional","affiliation":[{"name":"Department of Pneumophtysiology I, \u201cCarol Davila\u201d University of Medicine and Pharmacy, Dionisie Lupu Street, Nr. 37, Sector 2, 020021 Bucharest, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0005-8804-2663","authenticated-orcid":false,"given":"Ioan Emanuel","family":"Stavarache","sequence":"additional","affiliation":[{"name":"\u201cGrigore T. Popa\u201d University of Medicine and Pharmacy, 700115 Iasi, Romania"},{"name":"Department of Preclinical Disciplines, Faculty of Medicine, \u201cApollonia\u201d University of Ia\u015fi, 700511 Ia\u0219i, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6136-5204","authenticated-orcid":false,"given":"Ionel-Bogdan","family":"Cioroiu","sequence":"additional","affiliation":[{"name":"Romanian Academy-Iasi Branch, Research Center for Oenology, 700490 Iasi, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3252-7715","authenticated-orcid":false,"given":"Antigona Carmen","family":"Trofor","sequence":"additional","affiliation":[{"name":"\u201cGrigore T. Popa\u201d University of Medicine and Pharmacy, 700115 Iasi, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,1,15]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Fern\u00e1ndez-de-las-Pe\u00f1as, C., Palacios-Ce\u00f1a, D., G\u00f3mez-Mayordomo, V., Cuadrado, M.L., and Florencio, L.L. (2021). Defining Post-COVID Symptoms (Post-Acute COVID, Long COVID, Persistent Post-COVID): An Integrative Classification. Int. J. Environ. Res. Public. Health, 18.","DOI":"10.3390\/ijerph18052621"},{"key":"ref_2","unstructured":"(2025, November 18). COVID-19 Cases | WHO COVID-19 Dashboard. 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