{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,30]],"date-time":"2026-07-30T14:17:17Z","timestamp":1785421037848,"version":"3.56.0"},"reference-count":40,"publisher":"MDPI AG","issue":"3","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\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100002428","name":"Austrian Science Fund","doi-asserted-by":"publisher","award":["KLI 1064-B"],"award-info":[{"award-number":["KLI 1064-B"]}],"id":[{"id":"10.13039\/501100002428","id-type":"DOI","asserted-by":"publisher"}]},{"award":["KLI 1064-B"],"award-info":[{"award-number":["KLI 1064-B"]}],"id":[{"id":"https:\/\/ror.org\/013tf3c58","id-type":"ROR","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100010716","name":"Medical Scientific Fund of the Mayor of the City of Vienna City","doi-asserted-by":"publisher","award":["21176"],"award-info":[{"award-number":["21176"]}],"id":[{"id":"10.13039\/501100010716","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Med. Sci.","Medical Sciences"],"abstract":"<jats:p>Background: Despite normal lung imaging and preserved pulmonary and cardiac function, many patients with long COVID continue to experience persistent respiratory symptoms. This study aimed to quantify the pulmonary blood and airway volumes in patients with long COVID compared with healthy controls and to evaluate the associations of COVID-19 vaccination with these imaging parameters. Methods: Patients with long COVID presenting with persistent respiratory symptoms despite normal laboratory findings, pulmonary function tests, chest radiography, and chest computed tomography (CT) were prospectively enrolled. CT datasets were analyzed using functional respiratory imaging (FRI), incorporating the three-dimensional reconstruction and automated segmentation of the lungs, airways, and pulmonary vasculature. Quantitative imaging parameters were compared with those of historical healthy controls from the COPDGene study, matched for age, sex, body mass index, comorbidities, and pulmonary function test parameters. Results: Thirty patients with long COVID (mean 221 \u00b1 128 days after confirmed SARS-CoV-2 infection) and 30 matched healthy controls were included. Compared with controls, patients with long COVID demonstrated significantly lower pulmonary blood volumes in small and large pulmonary vessels, together with significantly reduced intrapulmonary airway volumes. Within the long COVID cohort, full COVID-19 vaccination was associated with a significantly greater small-vessel pulmonary blood volume and lobar airway volume compared with non-vaccinated individuals. Conclusions: These findings indicate that patients with long COVID exhibit persistent reductions in pulmonary blood and airway volumes despite normal conventional imaging and pulmonary function tests, suggesting the presence of subtle microvascular and small-airway abnormalities that may contribute to ongoing respiratory symptoms. The association between full COVID-19 vaccination and higher small-vessel pulmonary blood and lobar airway volumes suggests a potential protective effect on pulmonary structure and function; however, these findings require confirmation in larger, prospective controlled studies.<\/jats:p>","DOI":"10.3390\/medsci14030413","type":"journal-article","created":{"date-parts":[[2026,7,22]],"date-time":"2026-07-22T09:20:39Z","timestamp":1784712039000},"page":"413","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Beneficial Effect of COVID-19 Vaccination on Decreased Pulmonary Vascular and Airway Volumes of Patients with Long-COVID Syndrome"],"prefix":"10.3390","volume":"14","author":[{"given":"Eslam","family":"Samaha","sequence":"first","affiliation":[{"name":"Department of 1st Internal Medicine, Klinik Donaustadt, 1220 Vienna, Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3064-1277","authenticated-orcid":false,"given":"Emilie","family":"Han","sequence":"additional","affiliation":[{"name":"Division of Cardiology, 2nd Department of Internal Medicine, Medical University of Vienna, 1090 Vienna, Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8040-8086","authenticated-orcid":false,"given":"Dominika","family":"Lukovic","sequence":"additional","affiliation":[{"name":"Division of Cardiology, 2nd Department of Internal Medicine, Medical University of Vienna, 1090 Vienna, Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2505-8554","authenticated-orcid":false,"given":"Kevin","family":"Hamzaraj","sequence":"additional","affiliation":[{"name":"Division of Cardiology, 2nd Department of Internal Medicine, Medical University of Vienna, 1090 Vienna, Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2591-1380","authenticated-orcid":false,"given":"Jutta","family":"Bergler-Klein","sequence":"additional","affiliation":[{"name":"Division of Cardiology, 2nd Department of Internal Medicine, Medical University of Vienna, 1090 Vienna, Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ena","family":"Hasimbegovic","sequence":"additional","affiliation":[{"name":"Division of Cardiology, 2nd Department of Internal Medicine, Medical University of Vienna, 1090 Vienna, Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7083-2107","authenticated-orcid":false,"given":"Mariann","family":"Gy\u00f6ngy\u00f6si","sequence":"additional","affiliation":[{"name":"Division of Cardiology, 2nd Department of Internal Medicine, Medical University of Vienna, 1090 Vienna, Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,7,22]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"265","DOI":"10.1038\/s41586-020-2008-3","article-title":"A new coronavirus associated with human respiratory disease in China","volume":"579","author":"Wu","year":"2020","journal-title":"Nature"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"336","DOI":"10.1093\/cvr\/cvac115","article-title":"Long COVID and the cardiovascular system-elucidating causes and cellular mechanisms in order to develop targeted diagnostic and therapeutic strategies: A joint Scientific Statement of the ESC Working Groups on Cellular Biology of the Heart and Myocardial and Pericardial Diseases","volume":"119","author":"Alcaide","year":"2023","journal-title":"Cardiovasc. Res."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"m3026","DOI":"10.1136\/bmj.m3026","article-title":"Management of post-acute COVID-19 in primary care","volume":"370","author":"Greenhalgh","year":"2020","journal-title":"BMJ"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"603","DOI":"10.1001\/jama.2020.12603","article-title":"Persistent Symptoms in Patients After Acute COVID-19","volume":"324","author":"Carfi","year":"2020","journal-title":"JAMA"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"1009","DOI":"10.1136\/thoraxjnl-2020-215314","article-title":"Respiratory follow-up of patients with COVID-19 pneumonia","volume":"75","author":"George","year":"2020","journal-title":"Thorax"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"428","DOI":"10.1177\/01410768211032850","article-title":"Symptoms, complications and management of long COVID: A review","volume":"114","author":"Aiyegbusi","year":"2021","journal-title":"J. R. Soc. Med."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1787","DOI":"10.1039\/D4LC00848K","article-title":"Blood-perfused Vessels-on-Chips stimulated with patient plasma recapitulate endothelial activation and microthrombosis in COVID-19","volume":"25","author":"Weener","year":"2025","journal-title":"Lab. Chip."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"807","DOI":"10.1016\/S2213-2600(20)30225-3","article-title":"Pulmonary fibrosis and COVID-19: The potential role for antifibrotic therapy","volume":"8","author":"George","year":"2020","journal-title":"Lancet Respir. Med."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"e15","DOI":"10.1136\/archdischild-2023-325448","article-title":"SARS-CoV-2-related bronchiolitis: A multicentre international study","volume":"108","author":"Cozzi","year":"2023","journal-title":"Arch. Dis. Child."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"1295","DOI":"10.1152\/japplphysiol.00458.2022","article-title":"CT-derived measurements of pulmonary blood volume in small vessels and the need for supplemental oxygen in COVID-19 patients","volume":"133","author":"Dierckx","year":"2022","journal-title":"J. Appl. Physiol."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"e222087","DOI":"10.1148\/radiol.222087","article-title":"Detection of Post-COVID-19 Lung Abnormalities: Photon-counting CT versus Same-Day Energy-integrating Detector CT","volume":"307","author":"Prayer","year":"2023","journal-title":"Radiology"},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Tan, J., Bernatsky, S., Lee, J.L.F., Fortin, P.R., Dayam, R.M., Gingras, A.-C., Colmegna, I., Bowdish, D.M.E., Berger, C., and Chan, D. (2025). COVID-19 Breakthrough Infections in Immune Mediated Inflammatory Diseases: Data from the SUCCEED (Safety and Immunogenicity of COVID-19 Vaccines in Systemic Autoimmune-Mediated Inflammatory Diseases) Study. Vaccines, 13.","DOI":"10.3390\/vaccines13020104"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"517","DOI":"10.1016\/j.jaci.2025.07.030","article-title":"COVID-19 infection raises respiratory type 2 inflammatory disease risk, whereas vaccination is protective","volume":"157","author":"Olbrich","year":"2025","journal-title":"J. Allergy Clin. Immunol."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"32","DOI":"10.3109\/15412550903499522","article-title":"Genetic epidemiology of COPD (COPDGene) study design","volume":"7","author":"Regan","year":"2010","journal-title":"J. Chronic Obstr. Pulm. Dis."},{"key":"ref_15","unstructured":"Lauwers, E., Ides, K., Van Hoorenbeeck, K., Verhulst, S., De Backer, W., and Vos, W. (2021). Functional respiratory imaging in cystic fibrosis: Relation to classical respiratory outcomes. PLoS ONE, 16."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"2002110","DOI":"10.1183\/13993003.02110-2020","article-title":"Functional respiratory imaging provides novel insights in bronchopulmonary dysplasia","volume":"57","author":"Vanhaverbeke","year":"2021","journal-title":"Eur. Respir. J."},{"key":"ref_17","first-page":"1868","article-title":"Functional respiratory imaging as a tool to personalize respiratory treatment","volume":"59","author":"Vos","year":"2014","journal-title":"Respir. Care."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"1449","DOI":"10.1016\/j.acra.2020.07.019","article-title":"Assessment of Small Pulmonary Blood Vessels in COVID-19 Patients Using HRCT","volume":"27","author":"Lins","year":"2020","journal-title":"Acad. Radiol."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"1328","DOI":"10.1016\/S2213-2600(21)00385-4","article-title":"Addressing the post-acute sequelae of SARS-CoV-2 infection: A multidisciplinary model of care","volume":"9","author":"Parker","year":"2021","journal-title":"Lancet Respir. Med."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"231","DOI":"10.1164\/rccm.201301-0162OC","article-title":"Computed tomographic measures of pulmonary vascular morphology in smokers and their clinical implications","volume":"188","author":"Estepar","year":"2013","journal-title":"Am. J. Respir. Crit. Care Med."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"1900370","DOI":"10.1183\/13993003.00370-2019","article-title":"Pulmonary vascular density: Comparison of findings on computed tomography imaging with histology","volume":"54","author":"Rahaghi","year":"2019","journal-title":"Eur. Respir. J."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"454","DOI":"10.1164\/rccm.201811-2063OC","article-title":"Arterial Vascular Pruning, Right Ventricular Size, and Clinical Outcomes in Chronic Obstructive Pulmonary Disease. A Longitudinal Observational Study","volume":"200","author":"Washko","year":"2019","journal-title":"Am. J. Respir. Crit. Care Med."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"251","DOI":"10.1164\/rccm.202005-1671LE","article-title":"Pulmonary Vascular Pruning on Computed Tomography and Risk of Death in the Framingham Heart Study","volume":"203","author":"Synn","year":"2021","journal-title":"Am. J. Respir. Crit. Care Med."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"2004133","DOI":"10.1183\/13993003.04133-2020","article-title":"Altered pulmonary blood volume distribution as a biomarker for predicting outcomes in COVID-19 disease","volume":"58","author":"Morris","year":"2021","journal-title":"Eur. Respir. J."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"101695","DOI":"10.1016\/j.jbc.2022.101695","article-title":"The spike protein of SARS-CoV-2 induces endothelial inflammation through integrin alpha5beta1 and NF-kappaB signaling","volume":"298","author":"Robles","year":"2022","journal-title":"J. Biol. Chem."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"120","DOI":"10.1056\/NEJMoa2015432","article-title":"Pulmonary Vascular Endothelialitis, Thrombosis, and Angiogenesis in COVID-19","volume":"383","author":"Ackermann","year":"2020","journal-title":"N. Engl. J. Med."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"101","DOI":"10.1161\/CIRCULATIONAHA.120.047915","article-title":"Differentiating COVID-19 Pneumonia from Acute Respiratory Distress Syndrome and High Altitude Pulmonary Edema: Therapeutic Implications","volume":"142","author":"Archer","year":"2020","journal-title":"Circulation"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"E156","DOI":"10.1002\/ajh.25822","article-title":"Critically ill COVID-19 infected patients exhibit increased clot waveform analysis parameters consistent with hypercoagulability","volume":"95","author":"Tan","year":"2020","journal-title":"Am. J. Hematol."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"e241596","DOI":"10.1148\/radiol.241596","article-title":"Phase-resolved functional lung MRI reveals distinct lung perfusion phenotype in post-COVID-19 condition","volume":"314","author":"Voskrebenzev","year":"2025","journal-title":"Radiology"},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"Bazdar, S., Kwee, A.K.A.L., Houweling, L., de Wit-van Wijck, Y., Mohamed Hoesein, F.A.A., Downward, G.S., Nossent, E.J., Maitland-van der Zee, A.H., and on behalf of the P4O2 Consortium (2023). A systematic review of chest imaging findings in long COVID: Persistent bilateral lung abnormalities. J. Pers. Med., 13.","DOI":"10.3390\/jpm13020282"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"e221806","DOI":"10.1148\/radiol.221806","article-title":"Long-term lung abnormalities associated with COVID-19: Chest CT findings at 1-year follow-up","volume":"306","author":"Kanne","year":"2022","journal-title":"Radiology"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"233","DOI":"10.1186\/s12931-022-02163-x","article-title":"Pulmonary function and chest computed tomography abnormalities 6\u201312 months after recovery from COVID-19: A systematic review and meta-analysis","volume":"23","author":"Lee","year":"2022","journal-title":"Respir. Res."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"854","DOI":"10.1148\/radiol.10100322","article-title":"Validation of computational fluid dynamics in CT-based airway models with SPECT\/CT","volume":"257","author":"Vos","year":"2010","journal-title":"Radiology"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"872","DOI":"10.1016\/j.medengphy.2007.11.002","article-title":"Flow analyses in the lower airways: Patient-specific model and boundary conditions","volume":"30","author":"Vos","year":"2008","journal-title":"Med. Eng. Phys."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"182","DOI":"10.1136\/thoraxjnl-2020-215395","article-title":"Functional respiratory imaging identifies redistribution of pulmonary blood flow in patients with COVID-19","volume":"76","author":"Thillai","year":"2021","journal-title":"Thorax"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"244","DOI":"10.1186\/s12931-023-02549-5","article-title":"The effect of inhaled extrafine beclometasone dipropionate\/formoterol fumarate\/glycopyrronium bromide on distal and central airway indices, assessed using Functional Respiratory Imaging in COPD (DARWiIN)","volume":"24","author":"Skloot","year":"2023","journal-title":"Respir. Res."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"2607932","DOI":"10.1080\/25310429.2025.2607932","article-title":"Pulmonary blood volume redistribution in COVID-19 patients of different severity and its predictive value for six-month outcomes in the less pathogenic Omicron variant","volume":"32","author":"Hu","year":"2026","journal-title":"Pulmonology"},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"1746","DOI":"10.1056\/NEJMsb2408466","article-title":"Long COVID Defined","volume":"391","author":"Ely","year":"2024","journal-title":"N. Engl. J. Med."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"E383","DOI":"10.1148\/radiol.2021211396","article-title":"CT of Post-Acute Lung Complications of COVID-19","volume":"301","author":"Solomon","year":"2021","journal-title":"Radiology"},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"e232558","DOI":"10.1148\/radiol.232558","article-title":"Fleischner Society: Glossary of Terms for Thoracic Imaging","volume":"310","author":"Bankier","year":"2024","journal-title":"Radiology"}],"container-title":["Medical Sciences"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2076-3271\/14\/3\/413\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,7,22]],"date-time":"2026-07-22T09:51:41Z","timestamp":1784713901000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2076-3271\/14\/3\/413"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,7,22]]},"references-count":40,"journal-issue":{"issue":"3","published-online":{"date-parts":[[2026,7]]}},"alternative-id":["medsci14030413"],"URL":"https:\/\/doi.org\/10.3390\/medsci14030413","relation":{},"ISSN":["2076-3271"],"issn-type":[{"value":"2076-3271","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,7,22]]}}}