{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,24]],"date-time":"2026-10-24T06:01:06Z","timestamp":1792821666382,"version":"4.5.0"},"reference-count":136,"publisher":"MDPI AG","issue":"5","license":[{"start":{"date-parts":[[2025,4,30]],"date-time":"2025-04-30T00:00:00Z","timestamp":1745971200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Ministry of Research, Innovation, and Digitization, under the Romania\u2019s National Recovery and Resilience Plan","award":["760073\/23.05.2023"],"award-info":[{"award-number":["760073\/23.05.2023"]}]},{"name":"Ministry of Research, Innovation, and Digitization, under the Romania\u2019s National Recovery and Resilience Plan","award":["285\/30.11.2022"],"award-info":[{"award-number":["285\/30.11.2022"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Life"],"abstract":"<jats:p>Vitamin D has emerged as a potential modulator of immune responses, sparking interest in its role in COVID-19 susceptibility and clinical outcomes. This review synthesizes current clinical evidence and explores immunological insights into the relationship between vitamin D levels and COVID-19 infection severity. Epidemiological studies indicate an inverse correlation between vitamin D deficiency and an increased risk of severe disease, hospitalization, and mortality in COVID-19 patients. Immunologically, vitamin D exerts regulatory effects on both innate and adaptive immunity, enhancing antimicrobial defense mechanisms, reducing excessive inflammatory responses, and potentially mitigating cytokine storm events observed in severe COVID-19 cases. Despite promising observational data, clinical trials evaluating vitamin D supplementation have shown mixed results, underscoring the need for standardized dosing regimens and patient stratification. Future research should focus on large-scale randomized controlled trials to conclusively determine the therapeutic potential and optimal supplementation strategies for vitamin D in managing COVID-19.<\/jats:p>","DOI":"10.3390\/life15050733","type":"journal-article","created":{"date-parts":[[2025,5,4]],"date-time":"2025-05-04T20:42:37Z","timestamp":1746391357000},"page":"733","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":14,"title":["Vitamin D and COVID-19: Clinical Evidence and Immunological Insights"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-2274-6439","authenticated-orcid":false,"given":"Olga Adriana","family":"Caliman-Sturdza","sequence":"first","affiliation":[{"name":"Faculty of Medicine and Biological Sciences, Stefan cel Mare University of Suceava, 720229 Suceava, Romania"},{"name":"Suceava Emergency County Clinical Hospital, 720224 Suceava, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Roxana Elena","family":"Gheorghita","sequence":"additional","affiliation":[{"name":"Faculty of Medicine and Biological Sciences, Stefan cel Mare University of Suceava, 720229 Suceava, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Iuliana","family":"Soldanescu","sequence":"additional","affiliation":[{"name":"Integrated Center for Research, Development, and Innovation for Advanced Materials, Nanotechnologies, Manufacturing and Control Distributed Systems (MANSiD), Stefan cel Mare University of Suceava, 720229 Suceava, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,4,30]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"111106","DOI":"10.1016\/j.nut.2020.111106","article-title":"Increased risk for COVID-19 in patients with vitamin D deficiency","volume":"84","author":"Katz","year":"2021","journal-title":"Nutrition"},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Fakhoury, H.M.A., Kvietys, P.R., Shakir, I., Shams, H., Grant, W.B., and Alkattan, K. 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