Funding for this research was provided by:
the Major Project of National Science and Technology (2013ZX10004902)
a cooperation project of China Foundation for Hepatitis Prevention and Control, Chinese Center for Disease Control and Prevention and Shandong Provincial Center for Disease Control and Prevention (2014-32-R-019)
Taishan Scholar Program of Shandong Province (ts20151105)
the Shandong Medical Health Science and Technology Development Program (2011HD006, 2016WS0386)
Received: 7 April 2017
Accepted: 23 January 2018
First Online: 12 February 2018
Ethics approval and consent to participate
: The study protocol was approved by the Ethic Committee of Shandong CDC. Written consents were obtained from the participants ≥18 years old or the guardians for those < 18 years old in this study.
: Not applicable.
: The authors declare that they have no competing interests.
: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.