Received: 31 August 2019
Accepted: 15 March 2020
First Online: 12 June 2020
Ethics approval and consent to participate
: Ethical approval for the study has been obtained from the Human Subjects Ethics Sub-committee (HSESC) [HSEARS20180527001] of the Hong Kong Polytechnic University. All participants will be asked to indicate their willingness to participate by completing an informed consent form (Additional file InternalRef removed).
: Not applicable.
: The authors declare that they have no competing interests.