IL4 and hand, foot and mouth disease: The phase III clinical trial indicated that the low antibody titer (1:16) can effectively prevent EVA71-associated HFMD or herpangina (Zhu et al., 2014), which may be associated with the high levels of B lymphocyte humoral immune responses stimulated by the secretion of IL-4 (Kohlmeier and Woodland, 2009; Zhang et al., 2018).