Received: 5 December 2018
Accepted: 17 April 2019
First Online: 23 May 2019
Ethics approval and consent to participate
: The SDHS was approved by the Ethical Review Committee of the Shanghai Municipal Centers for Disease Control and Prevention. All the participants were fully informed of the purpose and procedures of the study and signed written consent forms before they enrolled in it.
: Not applicable.
: The study and our institution did not receive payments or services from a third party (government, commercial, private foundation, etc.) for any aspect of the submitted work (including but not limited to grants, data monitoring board, study design, manuscript preparation, statistical analysis, etc.) at any time. There are no relevant conflicts of interest. We have no financial relationships (regardless of amount of compensation) with entities, as described in the journal’s instructions. There are no relevant conflicts of interest. We have no patents, no matters planned, pending or issued, that are broadly relevant to the work or any other relationships/conditions/circumstances that might present a potential conflict of interest.
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