Document is current

Article History

Received: 14 January 2017

Accepted: 22 January 2018

First Online: 14 February 2018

Ethics approval and consent to participate

: Our study did not involve any health-related human participants’ interventions. The surveillance protocol was approved by the ethical committee of Shanghai Pudong New Area Center for Disease Control and Prevention. Verbal informed consent was obtained from each subject. Individual information was anonymized and de-identified prior to analysis. Strict confidentiality of individual data was practiced during the entire 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.