Severe COVID-19 patients have severe vitamin D deficiency in Northeast Mexico.

Objective: the association between vitamin D and COVID-19 severity is not consistent. We compared prevalences and analyzed the association between vitamin D deficiency and COVID-19 severity in Northeast Mexico. Methods: this was a cross-sectional study with individuals consecutively included at a referral diagnostic center during March-September 2020 (n = 181). Concurrently, every patient admitted to intensive care was also consecutively included (n = 116). Serum 25(OH)D < 20 ng/mL was considered vitamin D deficiency. Descriptive, ANOVA, and multivariate ordinal regression analyses were performed. Results: vitamin D deficiency prevalence was 63.8 % (95 % CI, 54.7, 72.0) in severe COVID-19; 25.6 % (95 % CI, 17.4, 36.0) in mild COVID-19; and 42.4 % (95 % CI, 33.2, 52.3) in non-diseased individuals. Vitamin D deficiency increased 5 times the odds of severe COVID-19 (95 % CI, 1.1, 24.3), independently of sex, age, body mass index, and inflammatory markers. Conclusions: this study is the first report of vitamin D deficiency in Northeast Mexico. Vitamin D deficiency was associated with COVID-19 severity.