- Congenital or acquired immunodeficiency, immunosuppressive therapy such as anti-cancer chemotherapy or radiation therapy within the preceding 6 months, or long-term systemic corticosteroid therapy injected or oral corticosteroids or other immunomodulator therapy within six weeks of the study vaccine. Individuals on a tapering dose schedule of oral steroids lasting < 7 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.