Vitamin D and COVID-19: comparative analysis with other respiratory infections and impact of comorbidities

Introduction The COVID-19 pandemic has promoted an intensive investigation into the pathophysiological mechanisms of SARS-CoV-2 infection, risk factors, and its impact on disease severity. Vitamin D has generated significant attention for its potential role in viral prevention and immune defense due to its pleiotropic functions, including immunomodulation and antimicrobial effects. This study aimed to assess serum 25(OH)D3 levels in patients with COVID-19 compared to those with other viral respiratory infections and to evaluate associations of vitamin D levels with symptomatology, clinical characteristics, presence of comorbidities and laboratory investigation. Methods The study included 78 patients admitted to a hospital with COVID-19 (52 patients) or other viral respiratory infections (26 patients). Routine blood biomarkers, markers of inflammation, markers of endothelial dysfunction, serum 25(OH)D3 were analyzed, and patients were classified according to vitamin D levels and presence of comorbidities. Results Most patients had vitamin D levels