On Feb. 22, 1995, the first inactivated hepatitis A vaccine, distributed by SmithKline Beecham Pharmaceuticals (Philadelphia, Pennsylvania), was licensed by the U.S. Food and Drug Administration (FDA) for use in persons aged greater than or equal to 2 years to prevent hepatitis A virus (HAV) infection.

Three intramuscular doses of the pediatric formulation are recommended for patients aged 2 to 18 (an initial dose, a second dose 1 month later, and a third at 6 to 12 months); adults required only two IM doses 6 to 12 months a part, and should be administered by intramuscular injection into the deltoid muscle.

Hepatitis A vaccine can be administered simultaneously with other vaccines and toxoids — including hepatitis B, diphtheria, tetanus, oral typhoid, cholera, Japanese encephalitis, rabies, and yellow fever — without affecting immunogenicity or increasing the frequency of adverse events. However, during simultaneous administration, the vaccines should be given at separate injection sites.

When immune globulin (IG) is given concurrently with the first dose of vaccine, the proportion of persons who develop protective levels of anti-HAV is not affected, but antibody concentrations are lower. Because the final concentrations of anti-HAV are substantially higher than that considered to be protective, this reduced immunogenicity is not expected to be clinically important.

Vaccination of an immune person is not contraindicated and does not increase the risk for adverse effects. Prevaccination serologic testing may be indicated for adult travelers who probably have had prior HAV infection if the cost of testing is less than the cost of vaccination and if testing will not interfere with completion of the vaccine series. Such persons may include those aged greater than 40 years and those born in areas of the world with a high endemicity of HAV infection.