[Vitamin D deficiency and suboptimal immunity : A challenge during Covid pandemia]

Vitamin D deficiencies are common throughout the world. In Switzerland, this deficiency affects every populations, including therefore people at risk of COVID-19 complications. Several studies demonstrate a correlation between vitamin D deficiencies and some chronic extraosseous pathologies. This literature review shows a correlation between the seriousness of symptoms, the deaths related to COVID-19 and a status of vitamin D deficiency. The effectiveness of a supplementation with vitamin D to improve those pathologies and limit complications due to COVID-19 is not yet clear because of the various methodological bias of the studies. However, the epidemiological extent of a vitamin D deficiency in our societies requires the coordinated actions of all health professionals in order to meet this public health challenge.