Primary Hypothesis: The proportion of initially seronegative subjects who receive vaccine within 14 days of exposure to an index case of hepatitis A disease and who have onset of a confirmed case of hepatitis A disease within 56 days of exposure will be similar to the proportion of initially seronegative subjects who receive IG within 14 days of exposure to an index case and who have onset of a confirmed case of hepatitis A disease within 56 days of exposure. The date of exposure is defined as the date of onset of clinical symptoms in the index case.