This study, conducted by several Iranian and American research institutes, investigated the association between vitamin D levels and its effect on several adverse clinical outcomes and parameters related to immune function and mortality rate in 235 COVID-19 patients. This study showed a significant association between vitamin D sufficiency, less severe clinical complaints, and better clinical (blood) parameters that significantly influence immune function. Additionally, a lower mortality rate was observed (9.7% in patients with sufficient vitamin D levels compared to 20% in vitamin D deficient patients). Therefore, the scientists recommend improving vitamin D levels by supplementation in the general population. More details can be found in the study.
Maghbooli et al.