IMMUNOGENICITY OF A RECOMBINANT HEPATITIS-A VACCINE IN ADULTS

Objectives: To evaluate the immunogenicity and reactogenicity of a rec ombinant hepatitis B vaccine in health care staff under routine use an d unselected conditions and to investigate factors that influence the response to vaccination.Methods: This prospective postmarketing survei llance study was performed in unselected health care staff and their r elaties (age range, 12-60 years) at 58 hospitals. Overall, 880 subject s were administered a 20-mu g dose of a vaccine at 0, 1, and 6 months according to the prescribing information and under routine hospital pr actice, and they were tested for antibody to hepatitis B surface antig en after the third dose at the hospitals' routine laboratory. The prin cipal outcome measures wer antibody to hepatitis B surface antigen tit ers that were expressed as the seroprotection rate (SPR) (SPR [given a s a percentage], greater than or equal to 10 mlU/mL), spontaneously re ported adverse events, and geometric mean titers (in milli-internation al units per milliliter). Results: The compliance to the 3-dose schedu le under routine hospital practice was 98.1%. The immune response was good in all age groups, and the overall SPR was 97.8% at 1 month after the third dose in field conditions with unselected health care worker s. The SPR in vaccinees (age range, 40-59 years) was close to 95%. Age (P<.001), smoking (greater than or equal to 10 cigarettes per day) (P <.001), Broca index (>110%) (P<.001), antibody to hepatitis B surface antigen resting (>8 weeks after the last dose) (P=.03), chronic underl ying disease (P=.04), and male gender (P=.04) were factors associated with lower geometric mean titers in routine vaccine use. No serious ad verse events were reported. Conclusion: The large immune response that was elicited by this hepatitis B vaccine in adults under daily routin e field conditions reflected reality, with a high SPR also found in el derly and other persons with risk factors associated with a lower immu ne response.