1. Department of Laboratory Medicine and Pathology, Walter Sisulu University and National Health Laboratory Services (NHLS), Private Bag X5117, Mthatha 5099, South Africa
2. Department of Family Medicine, Walter Sisulu University, Private Bag X5117, Mthatha 5099, South Africa
3. Wits School of Public Health, 27 St Andrew Road, Parktown, Johannesburg 2193, South Africa
4. Department of Public Health, Walter Sisulu University, Private Bag X5117, Mthatha 5099, South Africa