Immunogenicity and estimation of antibody persistence following vaccination with an inactivated virosomal hepatitis A vaccine in adults: A 20-year follow-up study.

PURPOSE: This was a 20-year follow-up study to assess long-term persistence of protective antibody levels against the hepatitis A virus (HAV) in healthy participants vaccinated with 2 doses of inactivated hepatitis A vaccine (Epaxal®) between 1992 and 1995. METHODS: Blood samples for anti-HAV antibody concentrations were obtained during a follow-up visit 20years after vaccination and were analyzed in parallel with samples still available from previous visits using AxSYM® HAVAB 2.0 assay. RESULTS: Mean (SD) age of the participants was 44.71 (3.905) years at year 20 follow-up (N=95). Participants completing 0/12-month Epaxal® immunization regimen (N=94) had seroprotection rate of 100% (95% CI: 96.2, 100.0) with ⩾10mIU/mL seropositivity cut-off and 98.9% (95% CI: 94.2, 100.0) with ⩾20mIU/mL cut-off. With ⩾10mIU/mL cut-off, the estimated median duration of protection was 77.3years (95% CI: 71.8, 83.5) with 95% of the vaccinated participants predicted to be protected for at least 41.5years. At ⩾20mIU/mL cut-off, the estimated median duration of protection was 64.8years (95% CI: 60.1, 68.4) with 95% of the vaccinated participants predicted to be protected for at least 33years. Anti-HAV antibody geometric mean concentrations were higher in women (277.9; 95% CI: 217.7, 354.7) than in men (167.7; 95% CI: 125.2, 224.6). CONCLUSION: The data from this 20-year follow-up study confirm previous observations that two doses of Epaxal® provide protection against hepatitis A infection for at least 30years in over 95% of healthy participants.

Interchangeability and tolerability of a virosomal and an aluminum-adsorbed hepatitis A vaccine.

The interchangeability of virosomal (Epaxal) and aluminum-adsorbed (Havrix 1440) hepatitis A virus (HAV) vaccines was studied in 111 healthy adults who were vaccinated in a randomized, single-blind, crossover clinical trial. Anti-HAV antibody titers were measured at days 0 (first dose), 14, and 28, and months 3, 6, 12 (second dose), 13, 24, 36, 48, 60 and 72. Most subjects (>95%) had sero-converted 14 days after the first dose of either vaccine. The second dose with either vaccine induced a high antibody response in all vaccines, irrespective of the type of vaccine administered as the first dose. Although both vaccines were well tolerated, the incidence of local adverse events (in particular pain) was significantly lower in subjects receiving the virosomal vaccine. Six-year follow-up data did not reveal any significant differences between the vaccination groups.