1. Division of Pulmonology, Faculty of Health Sciences, Chris Hani Baragwanath Academic Hospital, University of the Witwatersrand , Chris Hani Road, Johannesburg, 1864 , South Africa
2. Division of Critical Care, Faculty of Health Sciences, Chris Hani Baragwanath Academic Hospital, University of the Witwatersrand , Chris Hani Road, Johannesburg, 1864 , South Africa
3. Division of Haematology, National Health Laboratory Service, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, 2193, South Africa
4. Division of Infectious Diseases, Faculty of Health Sciences, Chris Hani Baragwanath Academic Hospital, University of the Witwatersrand , Chris Hani Road, Johannesburg, 1864 , South Africa
5. Department of Internal Medicine, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, 2193, South Africa