IMMUNE-RESPONSE TO A SINGLE-DOSE OF A NEW -TYPE OF HEPATITIS-A VACCINE IN PATIENTS WITH SPLENECTOMY

Basic problem and objective: The immune response to parenteral antigen s is reduced in persons without spleen. The seroconversion rate was me asured after application of a new type of vaccine against hepatitis A (immunopotentiating reconstituted influenza virus virosome [IRIV]) in patients who had undergone a splenectomy after trauma. Patients and me thods: 26 patients (23 men and 3 women, mean age 34.9 +/- 9.7 [25-65] years) with anti-hepatitis A virus (HAV) antibody titres <20 mIU/ml (m aximally 17 mIU/ml) were given a single dose of 0.5 ml of the IRIV hep atitis A vaccine 1 to 14 (mean 9.4) years after splenectomy. Immediate ly after the immunisation and 14 and 28 days afterwards anti-HAV titre s were determined. A titre rise to <20 mIU/ml was counted as seroconve rsion. At the first and last titre measurement immunoglobulins, neopte rin and beta-microglobulin levels were also measured as additional mar kers. Results: The seroconversion rate was 69.2% (18/26) after 14 days (geometric titre mean: 39 mIU/ml) and rose to 88,5% (23/26) after 28 days (geometric titre mean 74 mIU/ml). Seroconversion occurred in the three nonresponders after a second dose of the vaccine. All measuremen ts of the immunological markers were within normal limits. Conclusion: A single dose of a new type of vaccine against hepatitis A confers ad equate protection even in those persons who had a splenectomy.