Group II: Participants who are vaccine naive receive no immunization. Each participant will have 5 clinic visits during the study. Blood is drawn at each visit for routine testing and immune system check. Sera is drawn from participants for neutralizing antibody determination. Approximately 3 weeks after immunization (Day 18), blood is drawn from participants of both groups for a plasmapheresis procedure in which platelets and plasma are removed. This process is repeated 1 week later. Immunoglobulin G (IgG) is purified from the plasma of vaccinated participants.