Funding for this research was provided by:
National Institute of Allergy and Infectious Diseases (R21 AI110264-01A1)
Received: 18 January 2018
Accepted: 23 January 2019
First Online: 4 February 2019
Ethics approval and consent to participate
: Participants provided written consent for study participation. The study was approved by the University of KwaZulu-Natal Biomedical Research Ethics Committee (BE421/14, Durban, South Africa) and the Partners Institutional Review Board (2014P001173, Boston, MA).
: Not applicable.
: The authors declare that they have no competing interests.
: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.