Funding for this research was provided by:
United States Agency for International Development (674-A-12-00029)
Received: 13 December 2018
Accepted: 7 May 2019
First Online: 31 May 2019
Ethics approval and consent to participate
: This study was approved by the Human Research Ethics Committee (Medical) of the University of the Witwatersrand (Wits HREC M141188). All participants provided written informed consent to participate in the study.
: Not applicable.
: The authors declare that they have no competing interests.
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