Safety and Immunogenicity Study of Venezuelan Equine Encephalomyelitis (VEE) Vaccine as Booster Vaccine in Adults

Inclusion Criteria: * Be 18 to 65 years old at time of consent * Have received VEE TC-83 vaccine * Have VEE plaque reduction neutralization 80% titers (PRNT80) \<1:20 * If female of childbearing potential, must agree to have a urine pregnancy test on the same day before each vaccination administration. (Exception: documented hysterectomy or \>3 years of menopause). The results must be negative. Females just agree not to become pregnant for 3 months after receipt of the last study treatment (vaccination). * Be considered at risk for exposure to VEE virus and who have submitted a Request for IND Vaccines for VDD vaccine. * Sign and date the approved informed consent document and HIPAA Authorization. * Have in their charts: * medical history (including concomitant medications) within 60 days of planned first administration of vaccine * physical examination and laboratory tests within 1 year * previous chest radiograph results and electrocardiogram * Be medically cleared for participation by an investigator (Examinations and/or tests may be repeated at the discretion of the PI). * Be willing to return for all follow-up visits. * Agree to report any adverse events (AEs) that may or may not be associated with administration of the vaccine for at least 28 days after administration and agree to report all serious adverse events (for example, resulting in hospitalization) for the duration of the subject's participation in the study. * Agree to defer blood donation for 1 year after receipt of the vaccine. Exclusion Criteria: * Have completed previous VEE C-84 vaccine study as a non-responder. * Have clinically significant abnormal laboratory results (including evidence of hepatitis C, hepatitis B carrier state) or elevated liver function tests (two times the normal range or at the discretion of the PI). * Have a personal history of an immunodeficiency or received treatment with an immunosuppressive medication, such as systemically administered glucocorticoids (eg, prednisone) within 1 month before planned administration of the vaccine or with other immunosuppressive therapies within 6 months of planned administration of the vaccine. Other immunosuppressive therapies include all cancer chemotherapeutic agents, drugs to prevent transplant rejection, interferons, monoclonal antibodies, protein kinase inhibitors, methotrexate, TNF (tumor necrosis factor) inhibitors, and any other drug determined to be immunosuppressive by the PI. Current administration of topical, inhalational, or intranasal glucocorticoids is not excluded. * Have confirmed HIV infection. * Have positive pregnancy test or be a breastfeeding female. * Have any known allergies to components of the vaccine: * Neomycin sulfate * Streptomycin * VEE virus, inactivated * Formaldehyde * Eggs * Human serum albumin * Guinea pig heart cells * Sodium bisulfite * Have had a previous serious allergic reaction to guinea pigs or guinea pig products. (Subjects who have known allergies to guinea pigs but whose allergic reactions were not severe may still participate in the study but should be referred to an allergy specialist for assessment and recommendation prior to vaccination). * Have received or plan to receive another vaccine or investigational product within 28 days of VEE vaccination. * Have any unresolved AE resulting from a previous immunization. * Have a medical condition that, in the judgment of the PI, would impact subject safety.