claim: serum 25d level on asthma admission associated with covid-19 stage and mortality
evidence_1: to evaluate associations of plasma 25(oh)d status with the likelihood of coronavirus disease (covid-19) infection and hospitalization.", "to investigate the association between serum 25-hydroxyvitamin d levels and its effect on adverse clinical outcomes, and parameters of immune function and mortality due to a sars-cov-2 infection.", "to examine ...the relationship between serum 25-hydroxy vitamin d (25(oh)d) level and covid-19 infection, its severity, and its clinical case characteristics.", 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  "to examine the relationship between serum 25-hydroxy vitamin d (25(oh)d) level and covid-19 infection, its severity, and its clinical case characteristics.")