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 antigens is reduced in persons without spleen. The seroconversion rate was measured 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 methods: 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 (maximally 17 mIU/ml) were given a single dose of 0.5 ml of the IRIV hepatitis A vaccine 1 to 14 (mean 9.4) years after splenectomy. Immediately after the immunisation and 14 and 28 days afterwards anti-HAV titres were determined. A titre rise to <20 mIU/ml was counted as seroconversion. At the first and last titre measurement immunoglobulins, neopterin and beta-microglobulin levels were also measured as additional markers. 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 measurements of the immunological markers were within normal limits. Conclusion: A single dose of a new type of vaccine against hepatitis A confers adequate protection even in those persons who had a splenectomy.