- Correspondence to Dr Jin Zhao, Shenzhen Center for Disease Control and Prevention, Shenzhen 518055, China; ; Professor Jinquan Cheng, Shenzhen Center for Disease Control and Prevention, Shenzhen 518055, China;
- Received November 8, 2018
- Revised January 8, 2019
- Accepted January 26, 2019
- First published March 27, 2019.
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