Funding for this research was provided by:
National Natural Science Foundation of China (81390540, 81390544, 81390541)
National Key Research and Development Program of China (2016YFC0900504, 2016YFC0900500, 2016YFC0900501)
Wellcome Trust (088158/Z/09/Z, 202922/Z/16/Z, 104085/Z/14/Z)
Chinese Ministry of Science and Technology (2011BAI09B01)
Kadoorie Charitable Foundation
Text and Data Mining valid from 2018-06-18
Received: 29 November 2017
Accepted: 23 May 2018
First Online: 18 June 2018
Ethics approval and consent to participate
: The study protocol was approved by the Ethics Review Committee of the Chinese Center for Disease Control and Prevention (Beijing, China: 005/2004) and the Oxford Tropical Research Ethics Committee, University of Oxford (UK: 025–04). All participants provided written informed consent before taking part in the study.
: The authors declare that they have no competing interests.
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