Immunogenicity of combined hepatitis A and B vaccine in elderly persons.

More and more elderly people travel to areas where hepatitis A and B are endemic. Their immune system is less effective than in young persons. Therefore, it has to be insured that these travelers have protective immunity after vaccination. In a retrospective study we measured anti hepatitis virus (anti-HAV) and anti-HBs in elderly persons (N = 104, mean age 54 years) after combined hepatitis A/B vaccination under every-day conditions. After complete vaccination only 36 (34.6%) had antibodies against both viruses. Only 23 (29%) of 80 vaccinees older than 40 years were protected against hepatitis B and 52 (65%) against hepatitis A. The response to the vaccination decreased with increasing age. Vaccination against hepatitis B-but not against hepatitis A-was also influenced by the presence of chronic disease. After one booster 87% of the anti-HAV negative vaccinees developed protective anti-HAV antibodies. Anti-HBs can be expected in about 50% of the HBV negative vaccinees with every single booster. These results indicate that combined hepatitis A/B vaccination is not very effective in elderly persons. After complete vaccination their anti-HAV and anti-HBs antibodies have to be controlled to insure protection. In case of vaccination-failure boosters are very effective.