In 1995, highly effective inactivated hepatitis A vaccines were first licensed in the United States for preexposure prophylaxis against hepatitis A virus (HAV) among persons aged [greater than or equal to] 2 years. In 2005, vaccine manufacturers received Food and Drug Administration approval for use of the vaccines in children aged 12-23 months (1).
The Advisory Committee on Immunization Practices (ACIP) issued recommendations for preexposure use of hepatitis A vaccine in 1996, 1999, and 2006 (1). Currently, ACIP recommends hepatitis A vaccination of all children at age 12-23 months, catch-up vaccination of older children in selected areas, and vaccination of persons at increased risk for hepatitis A (e.g., travelers to endemic areas, users of illicit drugs, or men who have sex with men) (1).
For decades, immune globulin (IG) has been recommended for prophylaxis after exposure to HAV (1). IG also has been recommended in addition to hepatitis A vaccine for preexposure prophylaxis for travelers to countries with high or intermediate hepatitis A endemicity who are scheduled to depart <4 weeks after receiving the initial vaccine dose. This report details updated recommendations, made by ACIP in June 2007, for prevention of hepatitis A after exposure to HAV and in departing international travelers (Box) and incorporates existing ACIP recommendations for prevention of hepatitis A (1).
BOX. Summary of updated recommendations for prevention of hepatitis A after exposure to hepatitis A virus (HAV) and in departing international travelers Postexposure prophylaxis Persons who recently have been exposed to HAV and who previously have not received hepatitis A vaccine should be administered a single dose of single-antigen hepatitis A vaccine or immune globulin (IG) (0.02 mL/kg) as soon as possible. * For healthy persons aged 12 months-40 years, single-antigen hepatitis A vaccine at the age-appropriate dose is preferred. * For persons aged >40 years, IG is preferred; vaccine can be used if IG cannot be obtained. * For children aged < 12 months, immunocompromised persons, persons who have had chronic liver disease diagnosed, and persons for whom vaccine is contraindicated, IG should be used. International travel All susceptible persons traveling to or working in countries that have high or intermediate hepatitis A endemicity should be vaccinated or receive IG before departure. Hepatitis A vaccine at the age-appropriate dose is preferred to IG. The first dose of hepatitis A vaccine should be administered as soon as travel is considered. * One dose of single-antigen hepatitis A vaccine administered at any time before departure can provide adequate protection for most healthy persons. * Older adults, immunocompromised persons, and persons with chronic liver disease or other chronic medical conditions planning to depart to an area in [less than or equal to] 2 weeks should receive the initial dose of vaccine and also simultaneously can be administered IG (0.02 mL/kg) at a separate anatomic injection site. * Travelers who elect not to receive vaccine, are aged <12 months, or are allergic to a vaccine component should receive a single dose of IG (0.02 mL/kg), which provides effective protection for up to 3 months. NOTE: Previous recommendations remain unchanged regarding 1) settings in which postexposure prophylaxis is indicated, and 2) timing of administration of postexposure prophylaxis.
Rationale and Methods for Updated Recommendations
When administered within 2 weeks of last exposure, IG is 80%-90% effective in preventing clinical hepatitis A. Despite previously available limited data suggesting that hepatitis A vaccine might be efficacious when administered after exposure (2), in the absence of an appropriately designed clinical trial comparing the postexposure efficacy of vaccine with that of IG, ACIP continued to recommend IG exclusively for postexposure use (1). Hepatitis A vaccine, if recommended for other reasons, could be given at the same time. ACIP was prompted to revisit these recommendations when findings became available from a randomized, double-blind noninferiority clinical trial comparing the efficacy of hepatitis A vaccine and IG after exposure to HAV (3).
The results of this clinical trial were presented to ACIP at its February 2007 meeting. During April-May 2007, the ACIP Hepatitis Vaccines Workgroup considered these results in a series of teleconferences. During these teleconferences, the workgroup also considered the experiences of other countries (e.g., Canada and the United Kingdom) where hepatitis A vaccine has been recommended for postexposure use for >5 years and reviewed data on the immunogenicity of hepatitis A vaccine, the risk for HAV transmission in various settings, and factors known to affect the severity of hepatitis A. Additionally, the workgroup took into account potential advantages of vaccine, recognized disadvantages of IG, and relevance of these data to existing recommendations for use of hepatitis A vaccine and IG in international travelers departing <4 weeks after receiving the first dose of hepatitis A vaccine. The workgroup also considered the likelihood that no additional postexposure efficacy data would become available, because of the difficulties of conducting postexposure efficacy studies of IG and vaccine.
Information provided by: Findarticles.com
