- Correspondence to L Zhang, Health Service Department, Health Service Institute, Shanghai, China;
- Received September 17, 2020
- Revision received December 12, 2020
- Accepted December 17, 2020
- First published February 5, 2021.
If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.