Received: 27 August 2019
Accepted: 4 November 2019
First Online: 19 November 2019
Ethics approval and consent to participate
: The study was approved by the University of Cape Town Human Research Ethics Committee (reference number 806/2016). Residents (or their legal representative where appropriate) expressing interest in participating provided written/telephonic informed consent prior to enrolment.
: Not applicable.
: The authors declare that they have no competing interests.