In mouse models, transient impairment of type 1 IFN signalling appears to enhance live viral vaccine immunogenicity by increasing antigen load [50], and observations of enhanced IFN responses in children to viral infections with relatively reduced involvement of the adaptive immune response indicate a finely balanced system with interferon being required to prevent disseminated disease from live viral vaccines, but also some evidence to suggest that IFN-induced antiviral activity may suppress the development of long-lasting adaptive immune responses. This evidence concerns the gene IFNA1 and viral infectious disease.