Affiliation: | a Influenza Virus Research Center, National Institute of Infectious Diseases, 4-7-1 Gakuen, Musashimurayama, Tokyo 208-0011, Japan b Aichi Prefectural Institute of Public Health, 7-6 Nagare, Tsujimachi, Kita-ku, Nagoya, Aichi 462-8576, Japan c Sakai City Institute of Public Health, 3-2-8 Kaichouhigashi, Sakai-ku, Sakai, Osaka 590-0953, Japan |