Table 1.

Overview of vitamin D deficiency in regions highly affected by COVID-19.

Country	Population of study	25(OH) D status	Prevalence
China [30]	364 Chinese men aged 60–75	Deficiency: <50 nmol/L Insufficiency: 50–75 nmol/L	72% 22%
Iran [31]	Meta-analysis of 48 studies including 1911 men and 3683 women (excluding pregnant women, children, and patients)	Deficiency: <50 nmol/L	Pooled prevalence 55.21% in men 64.71 in women
Italy and Spain [32]	420 patients ≥65 years old admitted to rehabilitation centers	Deficiency: <50 nmol/L Insufficiency: 50–75 nmol/L	94.3% 81.2%
United States [33]	26010 adults in the National Health and Nutrition Examination Survey 2001–2010	Deficiency: <50 nmol/L Insufficiency: 50–75 nmol/L	28.9% 41.4%
France [34]	297 subjects studied in January and February 2015	Deficiency: <50 nmol/L	75.1%
United Kingdom [35]	278 patients with chronic obstructive pulmonary disease, aged 41–92 years in London	Deficiency: <50 nmol/L	61.5%