Prevention of endemic icteric viral hepatitis by administration of immune serum gamma globulin.

In a further analysis of a randomized, double-blind study of 107,803 U.S. soldiers receiving either immune serum gamma globulin (ISG) or placebo, serum specimens from the first week of clinical illness from 210 soldiers consecutively hospitalized with icteric hepatitis were reexamined by using modern immunologic methods to test for evidence of hepatitis A and B. Prophylactic intramuscular injection of 5 or 10 ml of ISG containing antibody to hepatitis A virus and antibody to hepatitis B surface antigen provided significant protection against development of endemic type A, type B, and non-A, non-B icteric hepatitis for six months if it was administered before exposure. Failure to receive a second injection of either 5 or 10 ml of ISG permitted an occurrence of hepatitis that was not significantly different from that among subjects who failed to receive a second placebo injection. ISG at 2 ml appeared equally effective in preventing hepatitis A but may be less effective in preventing hepatitis B and non-A, non-B hepatitis.