1. School of Health Sciences, University of Manchester, Manchester M13 9PL, UK
2. Department of Public Health Pharmacy and Management, School of Pharmacy, Sefako Makgatho Health Sciences University, Molotlegi Street, Pretoria 0208, South Africa
3. South African Vaccination and Immunisation Centre, Sefako Makgatho Health Sciences University, Molotlegi Street, Pretoria 0208, South Africa
4. Department of Virology, School of Medicine, Sefako Makgatho Health Sciences University, Molotlegi Street, Pretoria 0208, South Africa