Rationale:

• Immunoglobulin is highly effective in preventing HAV infection if administered within 2 weeks of exposure.
• Hepatitis A vaccine is effective in preventing HAV infection among persons over age 1 and under age 40 if administered within 2 weeks of exposure to HAV.

Evidence

• In a trial of 1414 susceptible contacts of persons with hepatitis A randomly assigned to receive IgG vs. hepatitis A vaccine as postexposure prophylaxis, low rates of HAV infection in both groups indicated that both the vaccine and immunoglobulin provided good postexposure prophylaxis (69).
• Hepatitis A vaccine or immunoglobulin administered intramuscularly within 2 weeks of exposure is effective in preventing symptomatic infection among exposed persons (24; 33; 69; 70; 71; 72).
• When HAV infection does occur, symptoms are attenuated, and fecal shedding of virus may be limited (33; 70).
• In a study of contacts of persons with hepatitis A, 186 of 409 (45%) susceptible contacts received IgG and returned for testing. Of these, 64 (34%) were infected, 12 of whom were symptomatic. This suggests that while IgG might not prevent HAV infection in all persons, it does attenuate infections in most persons (73).
• A meta-analysis of six studies of immunoglobulin use for primary prevention or postexposure prophylaxis suggests that IgG is efficacious, but efficacy varies by study (74). Safety data are not reported in these studies.

Comments:

• Hepatitis A vaccine has advantages over immunoglobulin for postexposure prophylaxis. The vaccine is easier to obtain and administer, is less expensive, and induces long-term protection from HAV infection. A second dose of the vaccine is needed 6 months after the first dose to induce long-term protection.
• No data are available for hepatitis A vaccine vs. immunoglobulin for postexposure prophylaxis in children under age 1 or adults over age 40.
• Administer immunoglobulin as soon after exposure as possible; immunoglobulin and hepatitis A vaccine may be administered simultaneously (23).
• Uncontrolled studies suggest that hepatitis A vaccine given within 7 days of exposure may be an effective alternative to immunoglobulin (75).