Information on immune globulin from CDC

IG is a sterile preparation of concentrated antibodies made from pooled human plasma. IG provides protection against hepatitis A through passive transfer of antibody. IG is 80%‑90% effective in preventing clinical hepatitis A when administered before exposure or early in the incubation period after exposure. IG can be used for pre-exposure prophylaxis for travelers to areas of high or intermediate endemicity of hepatitis A, particularly when the planned departure is less than 2-4 weeks later. In this situation, immunity from vaccination might not have developed by the time of departure. Post-exposure prophylaxis with IG is effective if administered within 14 days of exposure. The primary routine indication for post-exposure prophylaxis is for household or other intimate contacts of persons with hepatitis A. In addition, post-exposure prophylaxis might be indicated when hepatitis A cases occur in some institutional settings (e.g., child day-care centers) and after some common source exposures (e.g., persons who ate food prepared by an infected food handler). Local and/or state health departments should be consulted regarding the use of IG for post-exposure prophylaxis in these settings.