{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,12,11]],"date-time":"2025-12-11T21:07:28Z","timestamp":1765487248043,"version":"build-2065373602"},"reference-count":79,"publisher":"MDPI AG","issue":"17","license":[{"start":{"date-parts":[[2025,9,4]],"date-time":"2025-09-04T00:00:00Z","timestamp":1756944000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Nutrients"],"abstract":"<jats:p>Background\/Objectives: Vitamin D is involved in immune regulation, and deficiency may increase susceptibility to SARS-CoV-2 infection. This study assessed vitamin D status and examined associations between serum 25-hydroxyvitamin D (25(OH)D) concentrations and demographic, anthropometric, and clinical factors, including SARS-CoV-2 infection, in a diverse urban UK patient population. Methods: We analysed 25(OH)D concentrations in 17,619 pre-COVID-19 vaccine patients (62% female) whose samples were routinely processed between January and June 2020 at St Thomas\u2019 Hospital, London, UK. SARS-CoV-2 RNA\/IgG test results (March 2020\u2013January 2021) were linked to these records. Associations were examined with age, BMI, sex, ethnicity, and laboratory data. Vitamin D deficiency was defined as 25(OH)D &lt;25 nmol\/L, and insufficiency as 25\u201350 nmol\/L. Results: Vitamin D deficiency was observed in 25% of Black, 21% of Asian, and 17% of White patients; insufficiency was found in 36%, 34%, and 33%, respectively. Serum 25(OH)D concentrations differed by sex in Black and White patients but not in Asian patients. A total of 485 patients (2.8%) were SARS-CoV-2 positive, with a median 25(OH)D concentration of 42 nmol\/L (IQR 25\u201366); 24.1% were deficient and 36.7% insufficient (60.8% total). Among deficient individuals, 38% were White (median age 67.5 years) and 35% Black (median age 52.0 years). Age and BMI were the most significant contributors to infection in White and Black patients, respectively. Conclusions: Vitamin D deficiency and insufficiency were common across all ethnic groups and associated with SARS-CoV-2 infection. Deficiency was most prevalent among Black patients. Vitamin D status should be monitored in patient populations, and deficiencies addressed to ensure adequacy of this nutrient for immune system regulation and possibly the reduction in respiratory infection risk, including COVID-19.<\/jats:p>","DOI":"10.3390\/nu17172861","type":"journal-article","created":{"date-parts":[[2025,9,4]],"date-time":"2025-09-04T08:08:46Z","timestamp":1756973326000},"page":"2861","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Vitamin D Status in a Large, Ethnically Diverse Patient Population Living in South East London at the Onset of the COVID-19 Pandemic: A Cross-Sectional Study Including a SARS-CoV-2 Positive Patient Subset"],"prefix":"10.3390","volume":"17","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-7349-9517","authenticated-orcid":false,"given":"Agata","family":"Sobczy\u0144ska-Malefora","sequence":"first","affiliation":[{"name":"The Nutristasis Unit, Synnovis, St. Thomas\u2019 Hospital, London SE1 7EH, UK"},{"name":"Faculty of Life Sciences and Medicine, King\u2019s College London, London SE1 1UL, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0624-428X","authenticated-orcid":false,"given":"Aleksander","family":"Sulkowski","sequence":"additional","affiliation":[{"name":"Faculty of Life Sciences and Medicine, King\u2019s College London, London SE1 1UL, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2477-2131","authenticated-orcid":false,"given":"Laurence","family":"Harbige","sequence":"additional","affiliation":[{"name":"Centre for Health and Life Sciences Research, London Metropolitan University, London N7 8DB, UK"},{"name":"Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"David","family":"Steed","sequence":"additional","affiliation":[{"name":"Application Management Services, Viapath, St. Thomas\u2019 Hospital, London SE1 7EH, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4786-9240","authenticated-orcid":false,"given":"Dominic Jon","family":"Harrington","sequence":"additional","affiliation":[{"name":"The Nutristasis Unit, Synnovis, St. Thomas\u2019 Hospital, London SE1 7EH, UK"},{"name":"School of Medicine, University of Surrey, Guildford GU2 7XH, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2025,9,4]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"900","DOI":"10.1136\/thoraxjnl-2021-217487","article-title":"Risk factors for developing COVID-19: A population-based longitudinal study (COVIDENCE UK)","volume":"77","author":"Holt","year":"2022","journal-title":"Thorax"},{"key":"ref_2","unstructured":"Intensive Care National Audit Research Centre (ICNARC) (2020). 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