Additional factors that affect viral infection severity and asthma exacerbation risk include the enhanced expression of viral receptors (such as ICAM-1, low density lipoprotein receptor [LDLR], and CDHR3) (197, 198), high body mass index of patients (199), excessive increase in blood eosinophils (patients with type 2-high asthma) (199), reproducible changes in the DNA methylome (200, 201), and disturbances in the airway microbiota (202, 203). This evidence concerns the gene ICAM1 and asthma.