The recent severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) has resulted in millions of confirmed cases of infection and death. Vitamin D modulates the adaptive and innate immune systems; therefore, vitamin D deficiency may be related to the severity of coronavirus disease 2019 (COVID-19).

This study was performed on 122 COVID-19 patients and 122 non-COVID-19 individuals to determine the possible relationship between vitamin D deficiency and COVID-19 severity. Besides, the relationship between vitamin D status and the severity of disease was investigated in 49 patients without an underlying disease. The COVID-19 severity was defined based on O2 saturation, respiratory rate, and pulmonary involvement. Also, vitamin D status was defined as follows: Vitamin D deficiency (< 30 ng/mL) and vitamin D sufficiency (≥ 30 ng/mL).

The mean age of 122 COVID-19 patients, including 71 (58.2%) male patients and 51 (41.8%) women patients, was 59 ± 16 years in this study, while the mean age of the controls, including 61 male participants and 61 female participants, was 48 ± 13 years (P < 0.05). The mean vitamin D level was 34.14 ± 1 ng/mL in the patients and 32.94 ± 1 ng/mL in the controls (P = 0.872). However, there was no significant correlation in none of all the 122 patients and 49 patients without an underlying disease (P = 0.074, P = 0.261).

Based on the present findings, the correlation between vitamin D status and COVID-19 severity was not significant neither in 122 patients, and nor in 49 patients without an underlying disease.