EFFICACY OF DIFFERENT DOSES OF IMMUNE SERUM GLOBULIN IN THE PREVENTION OF HEPATITIS-A - A 3-YEAR PROSPECTIVE-STUDY

Previous studies have shown that the administration of immune serum gl obulin (ISG) before exposure to hepatitis A virus prevents infection. The precise dose needed and the duration of the protection conferred a re unclear, however. In this study, ISG doses of 2 mL and 5 mL were us ed for preexposure prophylaxis, and their efficacies in reducing the a ttack rate of hepatitis A among Israel Defence Forces troops serving i n field units were compared. The attack rate during the first 4 months of follow-up was low and was similar regardless of the dose administe red (0.11/10,000 and 0.15/10,000 for 2 mL and 5 mL, respectively; P = 1.0). In the second and third 4-month intervals after immunization, at tack rates were higher (but not significantly so) among soldiers given 2 mL than among those given 5 mL. Twelve months after immunization, t he cumulative attack rate for hepatitis A was significantly different for the two groups (2.78/10,000 vs. 1.30/10,000; P < .05). Our data su ggest that preexposure immunization with 2 mL of ISG is as effective a s that with 5 mL in preventing hepatitis A for 4 months. The advantage of the 5-mL dose is evident 5-12 months after administration.