title: Evidence for a change in the epidemiology of hepatitis B virus infection after nearly two decades of universal hepatitis B vaccination in South Africa.
abstract: The hepatitis B vaccine has been part of the South African Expanded Program on Immunization since April 1995 but its long-term impact remains unknown. This study tested 1,206 sera collected from patients aged 1-25 years from various health facilities across the country for HBV serological markers and HBV DNA. Based on the year the vaccine was introduced, samples were stratified by age into pre- and post-vaccine introduction populations, which were then compared for evidence of immunity and chronic carriage using the Chi-square test. Where HIV status was known, subset analyses were performed. Immunity to HBV infection increased from 13.0% in the pre- to 57.0% in the post-vaccine introduction population (P < 0.001). This decreased with increasing age within the post-vaccine introduction population (76.1% for 1-5 years, 50.0% for 6-10 years, and 46.3% for 11-16 years). In addition, HBV chronic carriage was significantly (P = 0.003) reduced in the post- (1.4%) compared to the pre-vaccine introduction population (4.2%). The difference in prevalence of active HBV infection in the serologically exposed pre- and post-vaccine introduction populations was not statistically significant. Subset analyses showed that evidence of immunity was significantly (P < 0.001) higher in the HIV negative compared to the HIV positive subset in both populations. Universal hepatitis B vaccination has been a remarkable success, with a significant increase in immunity to HBV infection. The observation that HBV chronic carriage increases as immunity wanes over time calls into question whether the time has come to consider a pre-adolescence vaccine booster dose policy.
authors.affiliation: HIV and Hepatitis Research Unit, Department of Virology, University of Limpopo (Medunsa Campus) and National Health Laboratory Services, Pretoria, South Africa.
authors.forename: Edina
authors.initials: E
authors.lastname: Amponsah-Dacosta
authors.forename: Ramokone L
authors.initials: RL
authors.lastname: Lebelo
authors.forename: J Nare
authors.initials: JN
authors.lastname: Rakgole
authors.forename: Rosemary J
authors.initials: RJ
authors.lastname: Burnett
authors.forename: Selokela G
authors.initials: SG
authors.lastname: Selabe
authors.forename: M Jeffrey
authors.initials: MJ
authors.lastname: Mphahlele
mesh_terms: D000293:Adolescent; D000328:Adult; D002353:Carrier State / Q000453:epidemiology* / Q000517:prevention & control*; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D015658:HIV Infections / Q000150:complications; D006509:Hepatitis B / Q000453:epidemiology* / Q000517:prevention & control*; D017325:Hepatitis B Vaccines / Q000008:administration & dosage*; D006801:Humans; D007223:Infant; D008297:Male; D015995:Prevalence; D013019:South Africa / Q000453:epidemiology; D014611:Vaccination / Q000706:statistics & numerical data*; D055815:Young Adult
chemical_list: D017325:Hepatitis B Vaccines
keywords: booster dose; chronic carriage; hepatitis B vaccine; immunity