Validating the optimal dose of normal immunoglobulin for protection against hepatitis A

INTERVENTION: 2.5 IU/kg hepatitis A antibodies, which equates to 0.025mL/kg NHIG (Normal Human Immunoglobulin) as a single intramuscular (IM) dose CONDITION: hepatitis A PRIMARY OUTCOME: Quantitative hepatitis A antibody concentration in serum measured according to manufacturer's instructions using Beckmann Coulter Access HAV Ab kit. SECONDARY OUTCOME: Adverse events: local tenderness, erythema, muscle stiffness, pyrexia, malaise, drowsiness, urticaria, local swelling, headache, nausea, dizziness, any other events volunteered or observed. ; Participants will remain under observation for 20 minutes after NHIG administration. Participants will be questioned about any adverse events potentially related to NHIG administration when they return for blood sampling on days 1, 3 and 7. INCLUSION CRITERIA: Healthy adult volunteers who provide informed consent, and meet the following criteria will be eligible: o are immune to measles and rubella according to commercial serology test o are not immune to hepatitis A according to commercial serology test o are not eligible for free hepatitis A vaccination and unlikely to require hepatitis A vaccination during the course of study (ie no planned overseas travel) o weigh at least 51kg