Funding for this research was provided by:
National Natural Science Foundation of China (71303171, 71702131)
Received: 25 April 2020
Accepted: 23 July 2020
First Online: 10 August 2020
Ethics approval and consent to participate
: The study protocol was approved by The Ethical Committee of Tianjin University of Traditional Chinese Medicine, including collecting personal information. Written informed consent was required before the interviews, and participants were informed that they could refuse to answer any question. The questionnaire did not ask about infection status, and no biological samples were collected.
: Not Applicable.
: The authors declare that they have no competing interests.