Funding for this research was provided by:
University of Pretoria (Grant number: A0702)
National Health Laboratory Services (Grant number: 94445)
Received: 30 June 2019
Accepted: 19 August 2019
First Online: 14 September 2019
Ethics approval and consent to participate
: Ethical approval for this study was granted by the Research Ethics Committee, Faculty of Health Sciences, University of Pretoria. Ethics reference number: 709/2018.
: The authors declare that they have no competing interests.