1. Division of Infectious Diseases, Department of Internal Medicine, Taoyuan General Hospital, Ministry of Health and Welfare, Taoyuan 330, Taiwan
2. Institute of Public Health, School of Medicine, National Yang Ming Chiao Tung University, Taipei 112304, Taiwan
3. Gilead Sciences, Taipei 110, Taiwan
4. Department of Internal Medicine, Far Eastern Memorial Hospital, New Taipei City 220, Taiwan
5. School of Medicine, National Yang Ming Chiao Tung University, Taipei 112304, Taiwan