World Health Organization announced the novel coronavirus disease (COVID-19) outbreak to be a global pandemic. The distribution of community outbreaks shows seasonal patterns along certain latitude, temperature, and humidity i.e. similar to the behavior of seasonal viral respiratory tract infections. COVID-19 displays significant spread in northern midlatitude countries with an average temperature of 5-11 °C and low humidity. Vitamin D deficiency has also been described as pandemic, especially

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... n the Europe.Regardless of age, ethnicity, and latitude; recent data showed that 40% of the Europeans are vitamin D deficient (25(OH)D levels <50 nmol/L), and 13% are severely deficient (25(OH)D <30 nmol/L).A quadratic relationship was found between the prevalences of vitamin D deficiency in most commonly affected countries by COVID-19 and the latitudes. Vitamin D deficiency is more common in the subtropical and midlatitude countries than the tropical and high latitude countries. The most commonly affected countries with severe vitamin D deficiency are from the subtropical (Saudi Arabia; 46%, Qatar; 46%, Iran; 33.4%, Chile; 26.4%) and midlatitude (France; 27.3%, Portugal; 21.2% and Austria; 19.3%) regions. Severe vitamin D deficiency was found to be nearly 0% in some high latitude countries (e.g. Norway, Finland, Sweden, Denmark and Netherlands). Accordingly, we would like to call attention to the possible association between severe vitamin D deficiency and mortality pertaining to COVID-19. Given its rare side effects and relatively wide safety, prophylactic vitamin D supplementation and/or food fortification might reasonably serve as a very convenient adjuvant therapy for these two worldwide public health problems alike.