1. Wu Z, McGoogan JM. Characteristics of and important lessons from the coronavirus disease 2019 (COVID-19) outbreak in China: summary of a report of 72 314 cases from the Chinese Center for Disease Control and Prevention. JAMA. 2020;323(13):1239-42. PMID: 32091533 DOI: 10.1001/jama.2020.2648
2. Guan WJ, Liang WH, Zhao Y, Liang HR, Chen ZS, Li YM, et al. Comorbidity and its impact on 1590 patients with Covid-19 in China: a nationwide analysis. Eur Respir J. 2020;55(5):2000547. PMID: 32217650 DOI: 10.1183/13993003.00547-2020
3. Ilie PC, Stefanescu S, Smith L. The role of vitamin D in the prevention of coronavirus disease 2019 infection and mortality. Aging Clin Exp Res. 2020;32(7):1195-8. PMID: 32377965 DOI: 10.1007/s40520-020-01570-8
4. Kara M, Ekiz T, Ricci V, Kara Ö, Chang KV, Özçakar L. ‘Scientific Strabismus’ or two related pandemics: COVID-19 & vitamin D deficiency. Br J Nutr. 2020;124(7):736-41 PMID: 32393401 DOI: 10.1017/S0007114520001749
5. Wilder-Smith A, Freedman DO. Isolation, quarantine, social distancing and community containment: pivotal role for old-style public health measures in the novel coronavirus (2019-nCoV) outbreak. J Travel Med. 2020;27(2):taaa020. PMID: 32052841 DOI: 10.1093/jtm/taaa020
6. Gröber U, Spitz J, Reichrath J, Kisters K, Holick MF. Vitamin D: update 2013: from rickets prophylaxis to general preventive healthcare. Dermatoendocrinol. 2013;5(3):331-47. PMID: 24516687 DOI: 10.4161/derm.26738
7. Gunville CF, Mourani PM, Ginde AA. The role of vitamin D in prevention and treatment of infection. Inflamm Allergy Drug Targets. 2013;12(4):239-45. PMID: 23782205 DOI: 10.2174/18715281113129990046
8. Cannell JJ, Hollis BW. Use of vitamin D in clinical practice. Altern Med Rev. 2008;13(1):6-20. PMID: 18377099
9. Institute of Medicine (US) Standing Committee on the Scientific Evaluation of Dietary Reference Intakes. Dietary reference intakes. Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D, and Fluoride. Washington, D.C: National Academies Press (US); 1997.
10. Jones G. Extrarenal vitamin D activation and interactions between vitamin D2, vitamin D3, and vitamin D analogs. Annu Rev Nutr. 2013;33:23-44. PMID: 23642201 DOI: 10.1146/annurev-nutr-071812-161203
11. Palacios C, Gonzalez L. Is vitamin D deficiency a major global public health problem? J Steroid Biochem Mol Biol. 2014;144(Pt A):138-45. PMID: 24239505 DOI: 10.1016/j.jsbmb.2013.11.003
12. Miller JW, Harvey DJ, Beckett LA, Green R, Farias ST, Reed BR, et al. Vitamin D status and rates of cognitive decline in a multiethnic cohort of older adults. JAMA Neurol. 2015;72(11):1295-303. PMID: 26366714 DOI: 10.1001/jamaneurol.2015.2115
13. Khazai N, Judd SE, Tangpricha V. Calcium and vitamin D: skeletal and extraskeletal health. Curr Rheumatol Rep. 2008;10(2):110-7. PMID: 18460265 DOI: 10.1007/s11926-008-0020-y
14. Wang TJ, Zhang F, Richards JB, Kestenbaum B, Van Meurs JB, Berry D, et al. Common genetic determinants of vitamin D insufficiency: a genome-wide association study. Lancet. 2010;376(9736):180-8. PMID: 20541252 DOI: 10.1016/S0140-6736(10)60588-0
15. Ross AC, Manson JE, Abrams SA, Aloia JF, Brannon PM, Clinton SK, et al. The 2011 report on dietary reference intakes for calcium and vitamin D from the Institute of Medicine: what clinicians need to know. J Clin Endocrinol Metab. 2011;96(1):53-8. PMID: 21118827 DOI: 10.1210/jc.2010-2704
16. Lee JY, So TY, Thackray J. A review on vitamin d deficiency treatment in pediatric patients. J Pediatr Pharmacol Ther. 2013;18(4):277-91. PMID: 24719588 DOI: 10.5863/1551-6776-18.4.277
17. Dimeloe S, Nanzer A, Ryanna K, Hawrylowicz C. Regulatory T cells, inflammation and the allergic response-the role of glucocorticoids and vitamin D. J Steroid Biochem Mol Biol. 2010;120(2-3):86-95. PMID: 20227496 DOI: 10.1016/j.jsbmb.2010.02.029
18. Lee MD, Lin CH, Lei WT, Chang HY, Lee HC, Yeung CY, et al. Does vitamin D deficiency affect the immunogenic responses to influenza vaccination? A systematic review and meta-analysis. Nutrients. 2018;10(4):409. PMID: 29587438 DOI: 10.3390/nu10040409
19. Zhang R, Naughton DP. Vitamin D in health and disease: current perspectives. Nutr J. 2010;9(1):65. PMID: 21143872 DOI: 10.1186/1475-2891-9-65
20. Taylor CE, Camargo CA Jr. Impact of micronutrients on respiratory infections. Nutr Rev. 2011;69(5):259-69. PMID: 21521228 DOI: 10.1111/j.1753-4887.2011.00386.x
21. Grant WB, Lahore H, McDonnell SL, Baggerly CA, French CB, Aliano JL, et al. Evidence that vitamin D supplementation could reduce risk of influenza and COVID-19 infections and deaths. Nutrients. 2020;12(4):988. PMID: 32252338 DOI: 10.3390/nu12040988
22. Komatsuzawa H, Ouhara K, Yamada S, Fujiwara T, Sayama K, Hashimoto K, et al. Innate defences against methicillin‐resistant Staphylococcus aureus (MRSA) infection. J Pathol. 2006;208(2):249-60. PMID: 16362993 DOI: 10.1002/path.1898
23. Klotman ME, Chang TL. Defensins in innate antiviral immunity. Nat Rev Immunol. 2006;6(6):447-56. PMID: 16724099 DOI: 10.1038/nri1860
24. Schwalfenberg GK. A review of the critical role of vitamin D in the functioning of the immune system and the clinical implications of vitamin D deficiency. Mol Nutr Food Res. 2011;55(1):96-108. PMID: 20824663 DOI: 10.1002/mnfr.201000174
25. Rondanelli M, Miccono A, Lamburghini S, Avanzato I, Riva A, Allegrini P, et al. Self-care for common colds: the pivotal role of vitamin D, vitamin C, zinc, and echinacea in three main immune interactive clusters (physical barriers, innate and adaptive immunity) involved during an episode of common colds—practical advice on dosages and on the time to take these nutrients/botanicals in order to prevent or treat common colds. Evid Based Complement Alternat Med. 2018;2018:2813095. PMID: 29853961 DOI: 10.1155/2018/5813095
26. Bouillon R, Garmyn M, Verstuyf A, Segaert S, Casteels K, Mathieu C. Paracrine role for calcitriol in the immune system and skin creates new therapeutic possibilities for vitamin D analogs. Eur J Endocrinol. 1995;133(1):7-16. PMID: 7627339 DOI: 10.1530/eje.0.1330007
27. Vásárhelyi B, Sátori A, Olajos F, Szabó A, Bekő G. Low vitamin D levels among patients at Semmelweis University: retrospective analysis during a one-year period. Orv Hetil. 2011;152(32):1272-7. PMID: 21803724 DOI: 10.1556/OH.2011.29187
28. Kohlmeier M. Avoidance of vitamin D deficiency to slow the COVID-19 pandemic. BMJ Nutr Prev Health. 2020;3(1):67-73. PMID: 33230496 DOI: 10.1136/bmjnph-2020-000096
29. Arvinte C, Singh M, Marik PE. Serum levels of vitamin C and vitamin D in a cohort of critically ill COVID-19 patients of a North American community hospital intensive care unit in May 2020: a pilot study. Med Drug Discov. 2020;8:100064. PMID: 32964205 DOI: 10.1016/j.medidd.2020.100064
30. Luo X, Liao Q, Shen Y, Li H, Cheng L. Vitamin D deficiency is inversely associated with Covid-19 incidence and disease severity in Chinese people. J Nutr. 2021;151(3):742-3. PMID: 33704501 DOI: 10.1093/jn/nxaa460
31. Hosack T, Baktash V, Mandal AK, Missouris CG. Prognostic implications of vitamin D in patients with COVID-19. Eur J Nutr. 202;60(1):549-50. PMID: 33225401 DOI: 10.1007/s00394-020-02429-4
32. Aygun H. Vitamin D can prevent COVID-19 infection-induced multiple organ damage. Naunyn Schmiedebergs Arch Pharmacol. 2020;393(7):1157-60. PMID: 32451597 DOI: 10.1007/s00210-020-01911-4
33. Chandran M, Maung AC, Mithal A, Parameswaran R. Vitamin D in COVID-19: dousing the fire or averting the storm?–A perspective from the Asia-Pacific. Osteoporos Sarcopenia. 2020;6(3):97-105. PMID: 32838048 DOI: 10.1016/j.afos.2020.07.003
34. Katz J, Yue S, Xue W. Increased risk for Covid-19 in patients with Vitamin D deficiency. Nutrition. 2021;84:111106. PMID: 33418230 DOI: 10.1016/j.nut.2020.111106
35. Liu N, Sun J, Wang X, Zhang T, Zhao M, Li H. Low vitamin D status is associated with coronavirus disease 2019 outcomes: A systematic review and meta-analysis. Int J Infect Dis. 2021;104:58-64. PMID: 33401034 DOI: 10.1016/j.ijid.2020.12.077
36. Farid N, Rola N, Koch EA, Nakhoul N. Active vitamin D supplementation and COVID-19 infections. Ir J Med Sci. 2021;6:1-4. PMID: 33409846 DOI: 10.1007/s11845-020-02452-8
37. Papadopoulos V, Li L, Samplaski M. Why does COVID‐19 kill more elderly men than women? Is there a role for testosterone? Andrology. 2021;9(1):65-72. PMID: 32681716 DOI: 10.1111/andr.12868