1. Influenza Division; Centers for Disease Control and Prevention; Atlanta GA USA
2. Influenza Program; Centers for Disease Control and Prevention; Pretoria South Africa
3. Centre for Respiratory Diseases and Meningitis; National Institute for Communicable Diseases of the National Health Laboratory Service; Johannesburg South Africa
4. School of Public Health; Faculty of Health Sciences; University of the Witwatersrand; Johannesburg South Africa
5. Global Immunization Monitoring and Surveillance Team, Expanded Programme on Immunization; Department of Immunization, Vaccines and Biological; World Health Organization; Geneva Switzerland
6. Centre for Viral Zoonoses; Department of Medical Virology; University of Pretoria; Pretoria South Africa
7. Tshwane Academic Division; National Health Laboratory Service; Pretoria South Africa
8. School of Pathology; Faculty of Health Sciences; University of the Witwatersrand; Johannesburg South Africa
9. Department of Medicine; Pietermaritzburg Metropolitan Hospital; Pietermaritzburg South Africa
10. Department of Medicine; University of KwaZulu-Natal; Pietermaritzburg South Africa
11. Department of Medicine; Klerksdorp-Tshepong Hospital Complex; Klerksdorp South Africa
12. Department of Medicine; Faculty of Health Sciences; University of the Witwatersrand; Johannesburg South Africa
13. Perinatal HIV Research Unit; University of the Witwatersrand; Johannesburg South Africa
14. Medical Research Council; Respiratory and Meningeal Pathogens Research Unit; University of the Witwatersrand; Johannesburg South Africa
15. Department of Science and Technology/National Research Foundation: Vaccine Preventable Diseases; University of the Witwatersrand; Johannesburg South Africa