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Article History

Received: 16 April 2020

Accepted: 30 September 2020

First Online: 13 October 2020

Ethics approval and consent to participate

: This study was approved by the Medical Ethics Committee of the Yunnan Center for Disease Control and Prevention, Yunnan, People’s Republic of China. Written informed consent was obtained from all adult participants and all parents/guardians of the study participants who were under the age of 16 years. Patients were informed that their participation was voluntary. Study participants were also informed about the purpose of the study. Confidentiality was maintained at all levels of the study. In addition, study participant involvement was on a voluntary basis, and participants who were unwilling to take part in the study and those who needed to quit their participation at any stage were told they could do so without any restrictions.

: Not Applicable.

: The authors declare that they have no competing interests.