Expert opinion and the literature supports the importance of humoral immunity and neutralizing antibodies in protection against measles, and antibody titers above 120–200 mIU/ml have been accepted as a correlate of protection.[1, 2, 3, 4, 5, 6, 13, 14] Antigen-induced B cell differentiation with the help of CD4+ T cells is recognized as a key biological phenomenon underlying the formation of ASCs (and memory B cells) to mount a protective anti-viral humoral immune response. This evidence concerns the gene CD4 and measles.