Hepatitis A vaccine: ready for prime time.

Two new inactivated hepatitis A vaccines are available that confer long-term protection against infection. They are indicated for pre-exposure prophylaxis in persons older than 2 years of age. For one vaccine preparation, Vaqta (Merck and Co., West Point, PA), the recommended schedule for adults is a 1.0-mL (50 U of hepatitis A viral antigen) intramuscular dose initially, followed by a booster dose 6-12 months later. Children 2-17 years of age should receive 0.5 mL (25 U of hepatitis A viral antigen) initially, followed by a booster dose 6-18 months later. The adult dosage schedule for Havrix (SmithKline Beecham, Philadelphia, PA) is a 1.0-mL (1440 enzyme-linked immunosorbent assay [ELISA] units) intramuscular dose initially, followed by a 1.0-mL booster dose 6-12 months later. Patients 2-18 years of age should receive doses of 0.5 mL (720 ELISA units). Primary candidates for vaccination are travelers to regions of endemic disease, children living in high-prevalence areas, homosexual males, users of illicit intravenous drugs, persons working directly with nonhuman primates or hepatitis A virus, patients older than 30 years of age with chronic liver disease, and persons who have received a liver transplant or are awaiting one. Seroconversion rates in healthy children and adults exceed 95%. Both vaccines are safe for use in pregnancy. The cost of the vaccine for adult patients is approximately $50 to $60.