claim: prevalence of antibodies to four human coronaviruses is higher in nasal secretions than in serum
evidence_1: another previous report by callow (4) suggested that hcov-229e-specific antibodies in serum and nasal wash specimens were correlated with protection from experimental infection with hcov-229e and disease, and iga antibodies to hcov-229e in nasal wash specimens were associated with a reduced duration of viral shedding in nasal secretions.", "based on the much lower frequency of patients with hcov-specific iga antibody in nasal wash specimens than of those with igg in serum in our older adult population, one might hypothesize that antibodies to hcov in nasal secretions decline in titer more rapidly after infection than do serum antibodies or that infection does not induce iga antibody to hcov in nasal secretions to high titers or at all in a significant proportion of older, chronically ill patients with copd.", 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  "hence, despite the near-universal presence of serum antibodies to the hcov strains in our study, the lower rates of detectable iga antibodies to hcov suggest a possible reason for susceptibility to reinfections with hcov, if iga antibodies in nasal secretions are indeed protective.")