The association between the level of serum 25(OH) vitamin D, obesity, and underlying diseases with the risk of developing COVID-19 infection: A case-control study of hospitalized patients in Tehran, Iran

Background and Objectives The outbreak of COVID-19 has created a global public health crisis. Little is known about the predisposing factors of this infection. The aim of this study was to explore an association between the serum vitamin D level, obesity, and underlying health conditions, as well as the vulnerability to COVID-19 in the Iranian population. Methods We conducted a case-control study of 201 patients with coronavirus infection and 201 controls. Cases and controls were matched for age and gender. The study was carried out for 2 months (February 2020-April 2020) at Imam Khomeini Hospital Complex, Tehran, Iran. Serum 25(OH) vitamin D was measured using the enzyme-linked immunosorbent assay method. Information containing age, gender, clinical symptoms, body mass index, computed tomography scan findings, and underlying health conditions related to each participant were elicited from health records. Results A significant negative correlation (p = .02) was observed between the serum vitamin D level and developing coronavirus infection. Also, the results showed that the COVID-19 cases were more likely to be overweight than the controls (p = .023). Diabetes mellitus, hypertension, and respiratory infections were found in 20.89%, 9.65%, and 6.96% of cases, respectively. These underlying health conditions were not significantly different between cases and controls (p = .81). Conclusions Vitamin D deficiency and obesity are two main predisposing factors associated with the vulnerability to coronavirus infection in the Iranian population.