How does immune globulin (IG) work to prevent hepatitis A virus (HAV) infection?

IG provides protection against HAV infection through passive transfer of antibody. Depending on the IG dosage, protection lasts from 1 to 2 months.

When administered for preexposure prophylaxis, a dose of 0.1 mL/kg will provide protection for up to 1 month and a dose of 0.2 mL/kg will provide protection for up to 2 months. If longer term protection is required and vaccination is contraindicated, a dose of 0.2 mL/kg can be repeated every 2 months. There is no maximum number of times the bimonthly doses of IG may be repeated as long as hepatitis A prophylaxis is required.

For postexposure prophylaxis, the recommended dosage is 0.1 mL/kg.