Received: 25 July 2019
Accepted: 25 November 2019
First Online: 18 December 2019
Ethics approval and consent to participate
: The study was approved by the Biomedical Research Ethics Committee (BREC) of the University of KwaZulu-Natal, South Africa (BREC reference number BE309/14). All participants signed written consents before participation in study as required by Ethics Committee.
: Not applicable.
: The authors declare there were no competing interests.