the association between vitamin d serum level and severity of covid-19: a cross-sectional study

Background and purpose: this study aimed to determine the association between vitamin d serum levels and the severity of covid-19 in iran. materials and methods: this cross-sectional study was done on 121 covid-19 patients referred to kowsar hospital of semnan city, iran, in 2022. the patients were assigned to the mild/moderate (n=80) and severe (n=41) covid-19 groups. the data collection tool was a checklist that included demographics, clinical variables, and laboratory parameters extracted from the medical file and interviews with the patient. also, patients’ serum vitamin d level was measured using the liquid chromatography-tandem mass spectrometry method. data were entered in stata software, version 14 and analyzed by multivariate logistic regression. p<0.05 were considered significant. results: the mean age of severe and mild/moderate groups were 67.66±16.15 and 48.5±18.7 years, respectively. about 61% and 55% of mild/moderate and severe groups were male. the multivariate logistic regression model showed vitamin d (odds ratio [or]=0.55; 95% ci, 0.42%, 0.83%) is the most important factor predicting the severity of covid-19 so that, for one ng/ml increase in vitamin d level, the odds of contracting the severe form of covid-19 decreases by about 45%. conclusion: the present study shows that low vitamin d levels may increase the risk of severe covid-19. however, further studies with larger sample sizes are recommended.