No significant association between vitamin D and COVID-19. A retrospective study from a northern Italian hospital

The world is currently overwhelmed by a novel coronavirus disease (COVID-19). Clinically, COVID-19 shows a broad range of manifestations: from asymptomatic to severe and possibly lethal interstitial pneumonia. Several studies suggested the involvement of Vitamin-D (VitD) in reducing the risk of COVID-19 infections/severity. However, most of them are based on circumstantial evidences, like the association between latitude-related sunlight exposure and mortality rate, while studies based on patients' VitD measurements are still scarce. Therefore, we retrospectively analyzed the VitD levels (measured as 25-hydroxyvitamin-D) from a cohort of 347 patients admitted to a northern Italian Hospital as suspected COVID-19s. Of them, 128 were positive (83 males, aged 62.7 ± 14.2 and 45 females, aged 69.3 ± 15.6) and 219 were negative (107 males, aged 62.8 ± 19.5 and 112 females, aged 54.3 ± 20.1). The averaged VitD levels were similar in the two groups: 21.8 ± 16.1 ng/mL and 22.8 ± 14.0 ng/mL for the COVID-19 positive and negative group respectively (p-value: 0.39), as well as the percentage of individuals having VitD levels below 30 ng/mL: 78.9% and 73.5% for the COVID-19 positive and negative group respectively. Because a large portion of patients were below the suggested 30 ng/mL threshold, we can't exclude that VitD supplementation, restoring normal levels, might be beneficial in reducing the risk of infection.