Viral Infections, Including Influenza and Corona Virus Disease 2019, and Vitamin D: A Mini-Review

Abstract

Recent research about the influence of vitamin D (VD) deficiency on the occurrence of viral infections suggests that children with VD deficiency have attenuated immune response. This, in turn, increases the severity of viral infections, especially those of the respiratory tract, that show a typical seasonality pattern during the winter months. Despite the immunization of children at the global level, outbreaks of influenza do frequently occur. Over the past months, we have witnessed that the explosive pandemic of the corona virus disease 2019 (COVID-19) has caused significant mortality in some countries. Numerous studies have shown that VD deficiency is increasingly prevalent worldwide, and that it is potentially associated with the onset of viral infections. Persons with hypovitaminosis D and subsequent secondary immunodeficiencies ought to be identified and treated, while preventive supplementation of VD should be recommended to the general population to avoid VD deficiency during the winter. In this way, the burden of viral infections on population health and economy could be reduced. This paper also reviews the influence of VD on infections caused by hepatitis B and C viruses, human papillomavirus, Epstein–Barr virus, Human herpes virus 6, herpes simplex virus, and human immunodeficiency virus.