HLA-B and COVID-19: Some studies in patients with more severe COVID-19 have shown cross-reactivity with autoantigens and suggest that the virus shares an immunoreactive epitope with HLA-B series antigens.[11,12] In many studies on BD, we have also found that the HLA-B family of antigens tends to be significantly elevated in BD patients,[13] a finding that reinforces our concern that BD patients are more susceptible to COVID-19 infection than the general population, and even further exacerbates the worsening of clinical symptoms in BD.