Funding for this research was provided by:
Centers for Disease Control and Prevention (U01IP000499)
Received: 7 December 2018
Accepted: 19 June 2019
First Online: 29 July 2019
Ethics approval and consent to participate
: This study was approved by the University of Michigan Institutional Review Board (HUM00075236). All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
: Not applicable.
: The authors declares that they have no competing interests.