Published on in Vol 23, No 3 (2021): March
Preprints (earlier versions) of this paper are
available at
https://preprints.jmir.org/preprint/24673, first published
.
1 Longhua District Center for Disease Control and Prevention, Shenzhen, China
2 Department of Early Childhood Education, The Education University of Hong Kong, Hong Kong, China
3 JC School of Public Health and Primary Care, The Chinese University of Hong Kong, Hong Kong, China