- Subjects meeting any of the following criteria will be temporarily excluded from the study: high-dose corticosteroid therapy (5-30 mg/kg/day) during the 24 hours immediately prior to the vaccine; IVIG (intravenous immunoglobulin) within 4 months prior to vaccine; platelet count of less than 20,000/ml within one month of vaccination with evidence of grade II or higher skin bleeding, assessed at vaccine administration