1 Department of Infectious Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, 1# Shuai Fu Yuan, Dongcheng District, Beijing, 100730, China.
2 Department of Infectious Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, 1# Shuai Fu Yuan, Dongcheng District, Beijing, 100730, China. litsh@263.net.