Low Serum 25-hydroxyvitamin D (Vitamin D) Level Is Associated With Susceptibility to COVID-19, Severity, and Mortality: A Systematic Review and Meta-Analysis
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8039288/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8039288/
Low Serum 25-hydroxyvitamin D (Vitamin D) Level Is Associated With Susceptibility to COVID-19, Severity, and Mortality: A Systematic Review and Meta-Analysis
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8039288/