[1] Natl Inst Infect Dis, Infect Dis Surveillance Ctr, Musashimurayama, Tokyo 2080011, Japan
[2] Fukushima Prefectural Inst Publ Hlth, Fukushima 9608560, Japan
[3] Yamagata Prefectural Inst Publ Hlth, Yamagata 9900031, Japan
[4] Jikei Univ, Sch Med, Dept Pediat, Tokyo 1058461, Japan
[5] Shigo Prefectural Inst Publ Hlth, Shiga 5200834, Japan
[6] Natl Inst Infect Dis, Dept Virol 3, Musashimurayama, Tokyo 2080011, Japan
[7] Gunma Prefectural Inst Publ Hlth & Environm Sci, Maebashi, Gunma 3710052, Japan