Received: 13 August 2018
Accepted: 30 January 2019
First Online: 11 February 2019
Ethics approval and consent to participate
: Ethical approval was obtained from the Health Research Ethics Committee of Stellenbosch University with reference number N14/02/013. Need for consent to participate was waived by the Health Research Ethics Committee of Stellenbosch University.
: Not applicable.
: The authors have no competing interests to declare.
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