Funding for this research was provided by:
National Natural Science Foundation of China (81170355, 81370592)
School of Medicine, Shanghai Jiao Tong University (DLY201609)
Received: 26 November 2019
Accepted: 10 March 2020
First Online: 20 March 2020
Ethics approval and consent to participate
: The present study protocol was reviewed and approved by the Ethics Committee of the Renji Hospital of Shanghai Jiao Tong University (ethics application no. 2016[63 k]). Before beginning work, we orally explained our study objectives and procedures to all participants, and obtained their permission to have their saliva specimens involved in our study. Meanwhile, written informed consents were signed by each participant. Each head of the selected households was responsible for giving them to us.
: Not applicable.
: The authors declare that they have no competing interests.