Immunogenicity and safety of a virosomal hepatitis A vaccine (Epaxal) in the elderly

BACKGROUND: Protection against hepatitis A virus (HAV) in the elderly is becoming more important as more senior travelers visit areas of high HAV endemicity, and less have protective antibodies acquired after natural infection during childhood. This study assessed the immunogenicity and safety of hepatitis A vaccine in elderly compared to young adults. METHODS: In this open, uncontrolled study, subjects of 18 to 45 years or < or = 50 years of age received two doses of aluminum-free, virosomal HAV vaccine, Epaxal (Berna Biotech Ltd, formerly Swiss Serum and Vaccine Institute, Bern, Switzerland) 12 months apart. RESULTS: After both the basic and the booster doses, geometric mean titers (GMT) for anti-HAV antibodies were 1.7-fold higher in subjects younger than 45 years compared with those < or = 50 years of age. The proportional increase in GMT after the booster dose, however, was similar in younger and older subjects. Seroprotection (< or = 20 mIU/mL) rates in the younger and older subjects were 100 and 65%, respectively, after the first vaccination and 100 and 97%, respectively, after the booster dose. Systemic and local adverse events were mainly mild and short-lived. CONCLUSION: These data show that HAV virosomal vaccine (Epaxal) is well tolerated and immunogenic in elderly subjects. The clinical relevance of lower seroconversion rates after the primary dose is unknown in this population of travelers.