1 Department of Laboratory Medicine, Beijing Hospital, National Center of Gerontology; Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, Beijing, the People's Republic of China.
2 Department of Clinical Diagnostic Centre, the Fifth Medical Centre, Chinese PLA (People's Liberation Army) General Hospital, Beijing, The People's Republic of China.
3 Chengdu Fifth People's Hospital, Chengdu, The People's Republic of China.
4 National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention and State Key Laboratory for Infectious Disease Prevention and Control, Beijing, The People's Republic of China.