Vitamin D Deficiency and COVID-19: A Case-Control Study at a Tertiary Care Hospital in Iran

Background: Areas with a higher prevalence of vitamin D deficiency have reported a higher frequency of severe coronavirus disease 2019 (COVID-19) infections. Objectives: This study aimed to assess the possible association between vitamin D and COVID-19. Methods: This study examined the vitamin D status, hepatic, serologic, and hematologic parameters of COVID-19 patients who tested positive upon admission to a major referral center in southwest Iran. A total of 50 cases and 50 controls were enrolled in the study after obtaining informed consent. The patients did not receive a vitamin D supplement during their hospitalization. Results: Patients with insufficiency and deficiency of vitamin D3 had a longer hospitalization time, a higher likelihood of ICU admission, and a greater risk of death compared to cases with sufficient levels of vitamin D. Conclusions: The results of this study showed that vitamin D deficiency is associated with increased severity and mortality rates. Therefore, using a vitamin D supplement may help reduce the severity of COVID-19.