title: Long-term immunogenicity of hepatitis B vaccination and policy for booster: an Italian multicentre study.
abstract: BACKGROUND
  Universal anti-hepatitis-B vaccination of infants and adolescents was implemented in Italy in 1991. We undertook a multicentre study in previously vaccinated individuals to assess the duration of immunity and need for booster, over 10 years after vaccination.
  
  
  METHODS
  In 1212 children and 446 Italian Air Force recruits vaccinated as infants and adolescents, respectively, we measured the concentrations of antibodies to hepatitis-B surface antigen (anti-HBs) and the presence of antibodies to hepatitis-B core antigen (anti-HBc) at enrollment; postimmunisation values were not available. Individuals positive for anti-HBc were tested for hepatitis B surface antigen (HBsAg) and hepatitis B viral DNA. Individuals with anti-HBs concentrations at 10 IU/L or more were regarded as protected; those with antibody less than 10 IU/L were given a booster dose and retested 2 weeks later. Individuals showing postbooster anti-HBs concentrations of less than 10 IU/L were offered two additional vaccine doses and retested 1 month after the third dose.
  
  
  RESULTS
  Protective anti-HBs concentrations were retained in 779 (64%, 95% CI 61.6-67) children and 398 (89%, 86.4-92.1) recruits. We recorded antibody amounts of less than 10 IU/L in 433 children (36%, 33-38.4) and 48 (11%, 7.9-13.6) recruits. One child and four recruits were positive for anti-HBc, but negative for HBsAg and hepatitis B viral DNA. Antibody concentrations were higher in recruits than in children (geometric mean titre 234.8 IU/L vs 32.1 IU/L, p=0.0001). 332 (97%) of 342 children and 46 (96%) of 48 recruits who received a booster showed an anamnestic response, whereas ten (3%) children and two (4%) recruits remained negative for anti-HBs or had antibody concentrations of less than 10 IU/L. Prebooster and postbooster antibody titres were strongly correlated with each other in both groups. All individuals given two additional vaccine doses (eight children and two recruits) showed anti-HBs amounts of more than 10 IU/L at 1 month after vaccination.
  
  
  CONCLUSIONS
  Strong immunological memory persists more than 10 years after immunisation of infants and adolescents with a primary course of vaccination. Booster doses of vaccine do not seem necessary to ensure long-term protection.
authors.affiliation: Istituto di Virologia, Università di Milano, Milan, Italy. alessandro.zanetti@unimi.it
authors.forename: Alessandro Remo
authors.initials: AR
authors.lastname: Zanetti
authors.forename: Andrea
authors.initials: A
authors.lastname: Mariano
authors.forename: Luisa
authors.initials: L
authors.lastname: Romanò
authors.forename: Raffaele
authors.initials: R
authors.lastname: D'Amelio
authors.forename: Maria
authors.initials: M
authors.lastname: Chironna
authors.forename: Rosa Cristina
authors.initials: RC
authors.lastname: Coppola
authors.forename: Mario
authors.initials: M
authors.lastname: Cuccia
authors.forename: Rossana
authors.initials: R
authors.lastname: Mangione
authors.forename: Fosca
authors.initials: F
authors.lastname: Marrone
authors.forename: Francesco Saverio
authors.initials: FS
authors.lastname: Negrone
authors.forename: Antonino
authors.initials: A
authors.lastname: Parlato
authors.forename: Emanuela
authors.initials: E
authors.lastname: Zamparo
authors.forename: Carla
authors.initials: C
authors.lastname: Zotti
authors.forename: Tommaso
authors.initials: T
authors.lastname: Stroffolini
authors.forename: Alfonso
authors.initials: A
authors.lastname: Mele
mesh_terms: D000328:Adult; D002648:Child; D004279:DNA, Viral / Q000032:analysis; D005260:Female; D006509:Hepatitis B / Q000276:immunology* / Q000517:prevention & control; D006510:Hepatitis B Antibodies / Q000097:blood*; D006512:Hepatitis B Core Antigens / Q000276:immunology; D006514:Hepatitis B Surface Antigens / Q000097:blood / Q000276:immunology; D017325:Hepatitis B Vaccines / Q000008:administration & dosage / Q000276:immunology*; D006515:Hepatitis B virus / Q000302:isolation & purification; D006801:Humans; D007115:Immunization Schedule; D007117:Immunization, Secondary; D008297:Male
chemical_list: D004279:DNA, Viral; D006510:Hepatitis B Antibodies; D006512:Hepatitis B Core Antigens; D006514:Hepatitis B Surface Antigens; D017325:Hepatitis B Vaccines