Funding for this research was provided by:
a grant from the Research Grants Council of the Hong Kong Special Administrative Region (17118518)
Received: 17 June 2020
Accepted: 15 September 2020
First Online: 21 September 2020
Ethics approval and consent to participate
: Ethical approval was obtained from the Institutional Review Board of the University of Hong Kong/Hospital Authority Hong Kong West Cluster (HKU/HA HKW IRB) (file No: UW 16–012). Written consent forms were signed by parents before the commencement of this study.
: Not applicable.