The first five years of universal hepatitis B vaccination in South Africa:evidence for elimination of HBsAg carriage in under 5-year-olds

South Africa implemented a vaccine against hepatitis B virus (HBV) into the Expanded Programme on Immunisation (EPI) in April 1995. The HBV vaccine is given at 6, 10, and 14 weeks, in parallel with OPV, DTP and Hib vaccines. This study assessed the impact of universal childhood HBV vaccination progr amme in reducing HBsAg carriage, in the first five years (1995-1999) since its implementation. In parallel, we investigated the current burden of HBV infection in mothers of vaccinees and the adult general population. A total of 598 babies (mean age = 23.3 months) who received 3 doses of 1.5 mug/0.5 mi Hepaccine-B (Cheil) were recruited from the Northern Province tone of t he nine provinces in South Africa). HBsAg, anti-HBs, anti-HBc, HBeAg and an ti-HBe were tested using the IMx or Axsym kits (Abbott Laboratories). PCR a ssays were performed following established protocols. The overall seroprote ction rate (i.e. anti-HBs titre greater than or equal to 10 mIU/ml) was 86. 8% (519/598) in vaccinated babies, while 13.2% had anti-HBs levels < 10 mIU /ml. Seroprotection rates and geometric mean titres (GMT) decreased signifi cantly with increasing age, possibly reflecting waning anti-HBs titre over time. Total HBV exposure (positive for either HBsAg, anti-HBs, or anti-HBc) was 31.0% (58/187) in mothers of vaccinees and 40% (72/180) in the adult g eneral population. HBsAg carrier rate was virtually similar in both groups (3.2% in mothers of vaccinees vs. 3.3% in the general population). Against this background, no vaccine failures resulting in HBsAg and HBV DNA positiv ity were seen in vaccinated babies, including 6 babies born to HBsAg positi ve carrier mothers tone carrier mother was positive for HBeAg and HBV DNA). However, 0.9% (5/582) babies, aged between 8-11 months, tested positive fo r anti-HBc, all of whom had anti-HBs titres > 10 mIU/ml and were negative f or HBV DNA. Anti-HBc positivity was probably maternal in origin, or may rep resent sub-clinical averted HBV infections. It can be concluded that the HB V vaccine is highly effective within the framework of the South African EPI and already shows a positive impact in the elimination of HBsAg carrier ra te in children < 5 years. (C) 2001 Elsevier Science Ltd. All rights reserve d.