case series. Because of the limited time, we did not perform new systematic review. We identified relevant literature up to 20 January 2020.

2.6.2 Search resources
We searched the bibliographic databases: PubMed, Embase, and Cochrane library.
We also searched following websites: the WHO (https://www.who.int/), CDC (Centers for Disease Control and Prevention, https://www.cdc.gov/), NICE (National Institute for Health and Clinical Excellence, https://www.nice.org.uk/), National Health Commission of the People’s Republic