As it has been reported that intranasal administration of HA antigen and IL-33 in BALB/c mice increased serum IgG1 as well as IgG2a (24), and the influenza infection after intranasal administration of IL-33 in mice produced IL-12p40 in BALF and increased IFN-γ production in the lung (31), the vaccine adjuvant effect of HP-β-CD in flu vaccine may induce type 1 immunity via IL-33. Here, IL33 is linked to influenza.