A critical update on the role of mild and serious vitamin D deficiency prevalence and the COVID-19 epidemic in Europe

OBJECTIVES: Coronavirus disease 2019 (COVID-19) has emerged as a pandemic, affecting nearly 180 million people worldwide as of June 22, 2021. Previous studies have examined the association between the mean vitamin D (Vit D) concentration of each country and COVID-19 infection and mortality rate in European countries. The aim of the present study was to critically evaluate the relationship between prevalence of mild and severe Vit D deficiency in each country and COVID-19 infection, recovery, and mortality using updated data and a different methodological approach. METHODS: Information on Vit D concentration or deficiency for each country was retrieved through a literature search. COVID-19 infections and mortalities per million people and total recoveries, as of June 22, 2021, were obtained. The associations between Vit D deficiency and COVID-19 infection, recovery, and mortality were explored using correlation coefficients and scatterplots. RESULTS: Non-significant correlations were observed between both number of COVID-19 infections (r = 0.363, P = 0.116) and number of recoveries (r = 0.388, P = 0.091) and the prevalence of mild Vit D deficiency (<50 nmol/L). Similarly, non-significant correlations were observed between both infections (r = 0.215, P = 0.392) and recoveries (r = 0.242, P = 0.332) and the prevalence of severe Vit D deficiency (<30 nmol/L). Significant correlations were found between COVID-19 mortality and prevalence of both mild Vit D deficiency (r = 0.634, P = 0.003) and severe Vit D deficiency (r = 0.538, P = 0.021). CONCLUSIONS: The prevalence of neither mild nor severe Vit D deficiency was associated with the number of COVID-19 infections in European countries. Thus, it is an important parameter to consider when implementing preventive measures to face COVID-19.