During 2009, the National Institute for Communicable Diseases (NICD), of the National Health Laboratory Service (NHLS), South Africa, maintained a central registry of all pH1N1 laboratory-confirmed cases detected throughout the country. The methodology of collating this data has previously been described in detail [23] . Briefly, we collated individual case-based data from all laboratories offering pH1N1 testing throughout South Africa, which included patient age, sex, dates of illness onset and specimen collection, and the administrative location (province) of the healthcare facility where the patient presented. Testing was performed by accredited laboratories, including: the National Influenza Centre (NICD-NHLS), NHLS public-sector laboratories or private-sector laboratories. All testing laboratories performed detection and characterisation of pH1N1 virus by real-time PCR by either the protocol developed by the WHO Collaborating Centre for Influenza, U.S. Centers for Disease Control and Prevention [24] , or using commercially available kits.