Public Health

Hepatitis A vaccine, immune globulin both suitable for postexposure prophylaxis

Last Updated: 2007-10-18 13:39:09 -0400 (Reuters Health)

By Anthony J. Brown, MD

NEW YORK (Reuters Health) - Findings from a new study show that hepatitis A vaccine offers comparable postexposure prophylaxis as immune globulin, which is known to be highly effective in preventing hepatitis A.

In certain high-risk groups, however, immune globulin may still offer the best protection. On the other hand, the vaccine offers certain advantages over immune globulin, including long-term protection, and is likely to be the preferred choice in many clinical situations, according to a report in The New England Journal of Medicine released Thursday.

The publication coincides with updated prophylaxis recommendations issued by the Centers for Disease Control and Prevention's Advisory Committee on Immunization Practice, appearing in the October 19th issue of the Morbidity and Mortality Weekly Report. The NEJM study results prompted the revisions.

A key change in the guidelines is the recommendation that people between 12 months of age and 40 years receive the hepatitis A vaccine for postexposure prophylaxis rather than immune globulin.

The study involved 1090 subjects in Kazakhstan, between 2 and 40 years of age, who had come into contact with hepatitis A patients. The subjects were randomized to receive the vaccine or immune globulin within 14 days of exposure. The main outcome measure was the occurrence of laboratory-confirmed, symptomatic hepatitis A within 15 to 56 days of exposure.

The average patient age was 12 years and most subjects received prophylaxis during the second week following exposure, lead author Dr. John C. Victor, from the University of Michigan in Ann Arbor, and colleagues note.

The percentage of infected subjects in the vaccine group was 4.4%, not significantly different from the 3.3% rate noted in the immune globulin group.

"The biggest finding we made was that the vaccine really does appear to work just about as good as immune globulin, at least in the healthy persons 2 to 40 years of age whom we studied," Dr. Victor told Reuters Health.

"Importantly," he pointed out, "our study put the vaccine to a pretty tough test, because most persons received vaccine in the second week postexposure, well into the incubation period of the virus. And vaccine passed."

Still, Dr. Victor emphasized that the vaccine may not be the right choice for all people, adding that although the difference in efficacy compared with immune globulin was not statistically significant, it might in some circumstance be clinically relevant.

Clinicians should "consider this possible difference," he advised, "and weigh it with the person's risk of infection, likelihood of severe illness with hepatitis A if infected, and vaccine's advantages over immune globulin when deciding with the patient whether to use vaccine or immune globulin."

The updated CDC guidelines for postexposure prophylaxis include:

--Using the vaccine as the first choice in patients between 12 months and 40 years of age.

--Using immune globulin as the first choice in patients over 40 years.

--Using immune globulin in children younger than 12 months, immunocompromised individuals, persons with chronic liver disease, and those with a contraindication to the vaccine.

The guidelines also discuss hepatitis A prophylaxis for people traveling to or working in endemic areas. The vaccine is the preferred option for younger healthy persons, while a combination of the vaccine and immune globulin is advised for older adults, immunocompromised adults, chronic liver disease patients, or patients with other chronic medical conditions.

N Engl J Med 2007;357:1685-1694.

Mor Mortal Wkly Rep CDC Surveill Summ 2007;56:1080-1084.