National Institute for Viral Disease Control and Prevention;
Chinese Center for Disease Control and Prevention Beijing 100052;
China;
Shandong Provincial Institute of Dermatology and STD;
Jinan 250022;
Shandong;
China;
Department of Social Medicine;
University of North Carolina;
Chapel Hill;
NC;
USA;
Department of Medicine;
University of North Carolina;
Chapel Hill;
NC;
USA;