ATLANTA — The hepatitis A vaccine should now be the first choice for postexposure prevention of hepatitis A infection in otherwise healthy people aged 12 months to 40 years.
The Centers for Disease Control and Prevention's Advisory Committee on Immunization Practices (ACIP) reached that conclusion based on postexposure data from a study that included 4,524 people. The hepatitis A vaccine was as effective as immunoglobulin in preventing hepatitis A in children and adults aged 12 months to 40 years who had been exposed to the viral infection.
ACIP's hepatitis A working group therefore recommended use of the hepatitis A vaccine for postexposure prophylaxis for anyone aged 12 months to 40 years, said ACIP member Dr. Tracy Lieu. The postexposure study did not include persons older than 40 years, so immunoglobulin is preferred for individuals older than age 40, but the hepatitis A vaccine can be used if immunoglobulin is not available, Dr. Lieu said. Only immunoglobulin should be used in special cases, such as in persons who are immunocompromised or in children younger than 12 months.
“These recommendations are pretty solid, and they are straightforward and simple for practitioners to follow,” said Dr. Lieu, who introduced the revised hepatitis A recommendations during ACIP's meeting. The panel voted to accept the recommendations.
Ryan Novak, Ph.D., a CDC epidemiologist, noted that the potential benefits of using hepatitis A instead of immunoglobulin include long-term protection, easier administration, and lower cost.
He presented results from a postexposure study that compared the effectiveness of the hepatitis A vaccine and of immunoglobulin for disease prevention after exposure to hepatitis A. In a randomized noninferiority study conducted in Almaty, a large city in Kazakhstan, the investigators enrolled 4,524 individuals aged 2–40 years with no history of hepatitis A, chronic liver disease, or allergy to the vaccine or to immunoglobulin. Ultimately, 1,414 individuals or their household or day care contacts were exposed to hepatitis A; 740 received the hepatitis A vaccine and 674 received immunoglobulin.
Overall, the hepatitis A vaccine was similar in effectiveness to immunoglobulin. The risk of developing hepatitis A was 4.7% in the vaccine group and 4.0% in the immunoglobulin group. “Putting this in context, the risk of hepatitis A among vaccine recipients was never more than 1.5% greater than among [immunoglobulin] recipients,” Dr. Novak said.
Most of the cases occurred in children, but the risk of developing hepatitis A was similar for adults in both groups. Of the 35 suspected cases of hepatis A in the vaccine group, 28 occurred in children and 7 occurred in adults aged 19–40 years. Of the 27 suspected cases in the immunoglobulin group, 20 occurred in children and 7 occurred in adults.
Questions remain about who can receive the hepatitis A vaccine for postexposure disease prevention, Dr. Novak acknowledged during the committee's discussion prior to voting.
“The vaccine clearly has long term benefits, and we'd like to extend those benefits to people over 40,” but more data are needed, he said. For people older than 40 years, immunoglobulin is preferred because of a lack of data regarding vaccine performance, he emphasized.
Also, children aged 12–24 months were not included in the study. Current preexposure recommendations for hepatitis A vaccination include 12- to 24-month-olds, but the committee agreed to leave the current immunoglobulin recommendations in place for children younger than 12 months.
Based on the new postexposure data, the panel also recommended these adjustments to the current CDC hepatitis A travel vaccination recommendations:
▸ The first dose of hepatitis A vaccine that is given at any time before travel should protect most healthy persons.
▸ In addition to the hepatitis A vaccine, anyone at increased risk of infection who will travel to places where hepatitis A is more common should receive immunoglobulin within 2 weeks before traveling.
▸ Infants younger than 12 months should receive immunoglobulin for preexposure protection from hepatitis A if they are traveling to a high-risk area.