1. State Key Laboratory for Infectious Disease Prevention and Control, National Center for AIDS/STD Control and Prevention, Chinese Center for Disease Control and Prevention, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, No. 155 Changbai Road, Changping District, Beijing 102206, China
2. Karamay Center for Disease Control and Prevention, Karamay 834000, China
3. Beijing Center for Disease Control and Prevention, Beijing 100013, China
4. School of Public Health, University of Maryland, College Park, MD 20742, USA
5. Department of Preventive Medicine, Vanderbilt University School of Medicine, Nashville, TN 37232, USA