Received: 25 November 2020
Accepted: 16 February 2021
First Online: 3 March 2021
: This study was performed in accordance with the ethical standards of the institutional and national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. It was reviewed by the Institutional review board of the University of Hong Kong/Hospital Authority Hong Kong West Cluster (reference no: UW 20–381) and was approved WITHOUT the need of informed consent.
: The authors declare no that they have no competing interests.