Funding for this research was provided by:
National Institutes of Health (1R01TW010286, R01AI125842)
National Science Foundation (1360330, 1646708)
University of California Berkeley (MRP-17-446315)
Received: 7 January 2019
Accepted: 4 July 2019
First Online: 12 July 2019
Ethics approval and consent to participate
: This study was approved by Committee for Protection of Human Subjects at the University of California, Berkeley, and all personally-identifiable data were removed from the dataset prior to analysis in this study. The requirement for written informed consent and assent was waived because this study only used routinely collected data by China Centers for Disease Control and Prevention as part of their standard public service mission, and posed no more than minimal risk to participants. Administrative authorization to access the data was obtained from Sichuan Center for Disease Control and Prevention.
: The authors declare that they have no competing interests.