1. Department of Infectious Diseases , Internal Medicine, , Sendai, Miyagi 980-8574 , Japan
2. Tohoku University Graduate School of Medicine , Internal Medicine, , Sendai, Miyagi 980-8574 , Japan
3. Department of Otolaryngology , Head and Neck Surgery, , Sendai, Miyagi 980-8574 , Japan
4. Tohoku University Graduate School of Medicine , Head and Neck Surgery, , Sendai, Miyagi 980-8574 , Japan
5. Department of Intelligent Network for Infection Control, Tohoku University Graduate School of Medicine , Sendai, Miyagi 980-8574 , Japan
6. Department of Virology, Tohoku University Graduate School of Medicine , Sendai, Miyagi 980-8575 , Japan
7. Department of Laboratory Medicine, Tohoku University Hospital , Sendai, Miyagi 980-8574 , Japan
8. Intensive Care Unit, Tohoku University Hospital , Sendai, Miyagi 980-8574 , Japan