In 1947, a new influenza virus without cross-reactive antisera against IAV (PR8) and IBV (Lee) was first isolated by R.M. Taylor from throat washings of a New York man during an influenza outbreak [177]. It was later designated type C and the first strain was named C/Taylor/1233/1947. ICV usually causes mild upper respiratory infection but can cause lower respiratory infection in children less than 2 years of age [178]. Most humans acquire antibodies to ICV at a young age [178,179] and antigenicity of ICV is stable, with no antigenic change being detected for at least 30 years [71]. These facts may be related to the limited outbreaks of ICV in humans, mainly in children. Although ICV antigenicity is stable, comparison of HE gene sequences in viruses isolated from 1947 to 2014 demonstrated that there are six lineages comprised of C/Taylor/1233/1947, C/Kanagawa/1/1976, C/Mississippi/1980, C/Aichi/1/1981, C/Yamagata/26/1981 and C/Sao Paulo/378/1982 [71]. ICVs have also been isolated from pigs [69] and cattle [70] (Table 1).