ACTIVE IMMUNIZATION AGAINST HEPATITIS-A - COMPARISON OF DIFFERENT IMMUNIZATION SCHEDULES

Three different immunization schedules were compared in 144 young, hea lthy adults (81 men, 63 women; mean age 28.5 years). They were randoml y assigned to one of three groups: group 1, immunization shots on day 0 and day 14 (n = 47), group 2, on day 0 and day 28 (n = 50), and grou p 3, on day 0, 14 and 28 (n = 47). All participants had a booster shot after one year. The seroconversion rate was 40-46% after first shot, 95-100% after the second one; all were anti-HAV positive after the boo ster injection. All subjects had specific antibodies in a mean concent ration of > 400 IU/l two weeks after the second shot. In almost all su bjects antibodies were demonstrable up to the 12th month after the fir st immunization (> 20 IU/l). Mean antibody concentration during the in terval between the second and third immunization after basal immunizat ion on day 0 and 14 or 0 and 28, respectively, was comparable. Three i nitial immunizations 14 days apart did not achieve much higher anti-HA V levels. The vaccine was equally well tolerated in all three groups. Thus basal immunization shortened to two injections two weeks apart pr esents a good alternative to the standard scheme of two injections fou r weeks apart. Three injections two weeks apart bring no demonstrable advantage.