Received: 1 March 2020
Accepted: 3 May 2020
First Online: 12 May 2020
Ethics approval and consent to participate
: Ethics approval was obtained from the Faculty of Health Sciences Research Ethics Committee of the University of Pretoria (ref. 539/2017). Institutional clearances were also obtained from the NHLS Academic Affairs, Research and Quality Assurance (for the public health sector data) as well as the relevant ethics committees of the respective private laboratories (for private health sector data).
: Not applicable.
: The authors declare that they have no competing interests.