Margarucci, L.M. et al. 2021. The role of vitamin D in prevention OF COVID-19 and its severity: an umbrella review: Vitamin D versus COVID-19: an Umbrella review. Acta Biomedica Atenei Parmensis. 92, S6 (Oct. 2021), e2021451. DOI:https://doi.org/10.23750/abm.v92iS6.12216.