title: Predicted 30-year protection after vaccination with an aluminum-free virosomal hepatitis A vaccine.
abstract: Few studies have examined the duration of protection following vaccination against hepatitis A virus (HAV) with currently licensed HAV vaccines. This study explored the long-term immunogenicity in individuals vaccinated with the virosomal hepatitis A virus, Epaxal. Adult volunteers (N = 130) previously enrolled into four different studies between 1992 and 1994 and who had completed a 0/12-month immunization regimen (primary and booster dose) were asked to participate in this follow-up study. Yearly anti-HAV titers up to 6 years following booster vaccination, and then once 9-11 years after booster were measured using two assays, Enzygnost and AxSYM HAVAB 2.0. Based on the Enzygnost assay, the seroprotection rate 9-11 years after booster was 100%, with a geometric mean concentration (GMC) of anti-HAV antibodies of 526 mIU/ml. Females had markedly higher GMCs than males (741 mIU/ml vs. 332 mIU/ml). Using an anti-HAV cut-off titer of >or=10 mIU/ml, a linear mixed mathematical model predicted a median duration of protection of 52.1 years. A duration of protection >or= 35.7 years was predicted for 95% of subjects. A more stringent cut-off of >or=20 mIU/ml shortened the median predicted duration of protection to 45.0 years. In conclusion, a two-dose Epaxal vaccination regimen confers in healthy adults a real-time protection of at least 9-11 years; this protection is predicted to last at least 30 years in over 95% of individuals. Further studies are necessary to assess the real duration of seroprotection and whether an additional booster is necessary later.
authors.affiliation: Travel and Migration Medicine Unit, Department of Community Medicine, Geneva University Hospitals, Geneva, Switzerland.
authors.forename: Patrick A
authors.initials: PA
authors.lastname: Bovier
authors.forename: Jürgen
authors.initials: J
authors.lastname: Bock
authors.forename: Tiziana Farinelli
authors.initials: TF
authors.lastname: Ebengo
authors.forename: Gert
authors.initials: G
authors.lastname: Frösner
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Glaus
authors.forename: Christian
authors.initials: C
authors.lastname: Herzog
authors.forename: Louis
authors.initials: L
authors.lastname: Loutan
mesh_terms: D000276:Adjuvants, Immunologic / Q000008:administration & dosage; D000293:Adolescent; D000328:Adult; D000535:Aluminum / Q000008:administration & dosage; D005260:Female; D005500:Follow-Up Studies; D006506:Hepatitis A / Q000517:prevention & control*; D035922:Hepatitis A Antibodies / Q000097:blood; D022362:Hepatitis A Vaccines / Q000276:immunology*; D006805:Human Experimentation; D006801:Humans; D007118:Immunoassay; D008297:Male; D008875:Middle Aged; D012737:Sex Factors; D013997:Time Factors; D022721:Vaccines, Virosome / Q000276:immunology; D014765:Viral Vaccines / Q000737:chemistry*; D055815:Young Adult
chemical_list: D000276:Adjuvants, Immunologic; D035922:Hepatitis A Antibodies; D022362:Hepatitis A Vaccines; D022721:Vaccines, Virosome; D014765:Viral Vaccines; C530970:epaxal berna; D000535:Aluminum