1. Medical Research Council, Respiratory and Meningeal Pathogens Research UnitFaculty of Health SciencesUniversity of the WitwatersrandJohannesburg South Africa
2. Department of Science/National Research Foundation: Vaccine‐Preventable DiseasesFaculty of Health SciencesUniversity of the WitwatersrandJohannesburg South Africa
3. Department of PaediatricsFaculty of Health Sciences, Chris Hani Baragwanath Academic HospitalUniversity of the WitwatersrandJohannesburg South Africa