Funding for this research was provided by:
South African Medical Research Council (SAMRC-RFAIFSP-01-2013/SA CRA 2.)
Received: 18 March 2021
Accepted: 10 October 2021
First Online: 3 November 2021
: This study only involved secondary analysis of anonymised individual-level data, and no attempt has been made to identify, even indirectly, the respondents.
: Not applicable.
: The authors declare that they have no competing interests.