Article History
Received: 3 December 2018
Revised: 28 January 2019
Accepted: 10 February 2019
First Online: 8 April 2019
Compliance with ethical standards
:
: The study was approved by the Human Research Ethics Committee of the University of the Witwatersrand (clearance certificate number M1409790), and has therefore been performed in accordance with the ethical standards laid down in the 1964 Declaration of Helsinki and its later amendments.
: None.