 - Received either immune globulin or other blood products within the last 3 months, or received injected or oral corticosteroids or other immunomodulator therapy within 6 weeks of the study vaccines. Individuals on a tapering dose schedule of oral steroids lasting 7 days and individuals e.g., asthmatics on a short schedule of oral steroids lasting 3 to 4 days may be included in the trial as long as they have not received more than one course within the last two weeks prior to enrollment. Topical steroids are not included in this exclusion criterion. 