1. Department of Public Health
2. Center for Infectious Disease Education and Research, China Medical University, Taichung, Taiwan
3. State Key Laboratory for Infectious Disease Prevention and Control, and National Center for AIDS/STD Control and Prevention, China Center for Disease Control and Prevention, Beijing, China
4. Department of Statistics, Feng Chia University, Taichung, Taiwan
5. Chaoyang Center for Disease Control and Prevention, Beijing, China