Hepatitis B sero-prevalence in children under 15 years of age in South Africa using residual samples from community-based febrile rash surveillance.

Introduction and Methods: Hepatitis B is a vaccine preventable disease and is notifiable in South Africa. Hepatitis B vaccination was incorporated into the Expanded Programme on Immunisation in South Africa in 1995. We used a convenience sample from community-based febrile rash surveillance in 2013 to estimate hepatitis B sero-prevalence. Of samples serologically negative for acute measles infection, 450 samples spanning nine provinces of South Africa were tested for hepatitis B surface antigen (HBsAg), hepatitis B surface antibody (anti-HBs) and hepatitis B core antibody (anti-HBc).
Results: Two children (2/450; 0.4%) tested positive for HBsAg. Three hundred and three children (67.3%) had evidence of vaccine induced immunity. Vaccine induced immunity was present in 80.2% of 1-5 year olds, but only 60.3% of 10-14 year olds. Natural immunity, indicating exposure to circulating hepatitis B, was present in 13/450 (2.9%) children.
Conclusion: Chronic hepatitis B in South African has decreased in prevalence from highly endemic levels prior to vaccine introduction to approximately 0.4% in this sample, demonstrating impact of a successful vaccination programme 18 years after introduction. Decreased vaccine-induced immunity with increasing age may reflect waning antibody titres over time.
Competing Interests: The authors perceive no conflicts of interest. The employer of all authors, the National Institute for Communicable Diseases, is funded by the South African government (www.nicd.ac.za). Dr Suchard administered during the conduct of the study; grants from Sanofi Pasteur, speaker honoraria from Aspen- GSK and Paediatric management group, consultancy fees from Prepex Circ Med Tech ltd and personal fees from World Health Organization, outside the submitted work; In addition, Dr. Suchard has an expired provisional South African patent 2010 “Method for Diagnosing a Disease” PA151392/P unrelated to the current work. This does not alter our adherence to PLOS ONE policies on sharing data and materials. Dr. Cohen reports grants from Sanofi Pastuer, non-financial support from Parexel, grants from US CDC, outside the submitted work. This does not alter our adherence to PLOS ONE policies on sharing data and materials.