According to professors at the Medical School of the National and Kapodistrian University of Athens (NKUA), one factor that has not been adequately analysed and can affect the outcome of COVID-19, are the levels of vitamin D in the population.
According to Maria Gavriatopoulou, Ioannis Danasis and Thanos Dimopoulos, recent data "suggest that vitamin D levels are related to the outcome of patients. In a relevant European data analysis across Europe, COVID-19 mortality was significantly correlated with vitamin D levels in different populations."
Low mortality rates are reported in the Nordic countries as an exception to the trend for worse outcomes in the far north, but the populations in these countries have a relative adequacy of vitamin D due to the extensive enrichment of food. Italy and Spain are also exceptions, but in these countries the deficiency of vitamin D is rather high.
Regarding Greece, the recommendation is to have adequate exposure to the sun, so that there are satisfactory levels of vitamin D, the professors underlined.
The role of vitamin D in the treatment of COVID-19 is considered to be twofold. "First, vitamin D supports the production of antimicrobial peptides in the respiratory epithelium, making it less likely to be infected with the SARS-CoV-2 virus and to develop COVID-19 symptoms. Second, vitamin D can help reduce the inflammatory response to SARS-CoV-2 infection, which has a positive effect on patients' outcome, as an excessive inflammatory response can lead to systemic manifestations that increase severity and complications of the disease."