Funding for this research was provided by:
Beijing Municipal Science and Technology Commission (D17110700670000)
Received: 15 November 2020
Accepted: 25 February 2021
First Online: 2 April 2021
: The study protocol was approved by Nankai University Health Research Ethics Committee and electronic individual informed consent was obtained before the online survey.
: Not applicable.
: The authors declare that they have no competing interests.