[1] Gunma Prefectural Inst Publ Hlth & Environm Sci, Maebashi, Gunma 3710052, Japan
[2] Chiba City Inst Hlth & Environm, Mihama Ku, Chiba 2610001, Japan
[3] Tochigi Prefectural Inst Publ Hlth, Utsunomiya, Tochigi 3291196, Japan
[4] Yamaguchi Prefectural Inst Publ Hlth & Environm, Yamaguchi 753082, Japan
[5] Aomori Prefectural Inst Publ Hlth & Environm, Aomori 0308566, Japan
[6] Tokyo Kasei Univ, Dept Nutr Sci, Itabashi Ku, Tokyo 1738602, Japan
[7] Natl Inst Infect Dis, Infect Dis Surveillance Ctr, Musashimurayama, Tokyo 2080011, Japan
[8] Natl Inst Infect Dis, Influenza Virus Res Ctr, Musashimurayama, Tokyo 2080011, Japan
[9] Natl Hosp Org Yokohama Med Ctr, Totsuka Ku, Yokohama, Kanagawa 2458575, Japan
[10] Natl Inst Infect Dis, Pathogen Genom Ctr, Musashimurayama, Tokyo 2080011, Japan