Beijing Research Center for Preventive Medicine - Beijing Center for Disease Prevention and Control, Beijing Research Center for Preventive Medicine - Beijing Center for Disease Prevention and Control, Beijing Research Center for Preventive Medicine - Beijing Center for Disease Prevention and Control, Beijing Research Center for Preventive Medicine - Beijing Center for Disease Prevention and Control, Capital Medical University - Department of Laboratory, Government of the People's Republic of China - Institute for Immunization and Prevention, Beijing Research Center for Preventive Medicine - Beijing Center for Disease Prevention and Control, Beijing Research Center for Preventive Medicine - Beijing Center for Disease Prevention and Control, Beijing Research Center for Preventive Medicine - Beijing Center for Disease Prevention and Control, Beijing Research Center for Preventive Medicine - Beijing Center for Disease Prevention and Control, Beijing Research Center for Preventive Medicine - Beijing Center for Disease Prevention and Control, Beijing Research Center for Preventive Medicine - Beijing Center for Disease Prevention and Control, Capital Medical University - Experimental Center for Basic Medical Teaching and Government of the People's Republic of China - Beijing Research Center for Preventive Medicine