Funding for this research was provided by:
National Institute of Allergy and Infectious Diseases (Y1-AI- 5072)
Received: 30 July 2018
Accepted: 15 January 2019
First Online: 29 January 2019
Ethics approval and consent to participate
: This study was approved by the Institutional Review Board of the Uniformed Services University of Health Sciences. All participants in the study provided informed consent prior to enrollment.
: Not applicable. (No individual-level data is presented.)
: The authors declare that they have no competing interests.