The study is designed to assess the safety and immunogenicity of Venezuelan Equine Encephalomyelitis Vaccine, Inactivated, Dried, C-84, TSI GSD 205, as a booster vaccination.

Study Objectives:

Primary:

To assess safety of Venezuelan Equine Encephalomyelitis Vaccine, Inactivated, Dried, C-84, TSI GSD 205, as a booster vaccination as a single dose or a three-dose series, and To assess immunogenicity of Venezuelan Equine Encephalomyelitis Vaccine, Inactivated, Dried, C-84, TSI GSD 205, as a booster vaccination as a single dose or a three-dose series

Secondary:

To assess incidence of VEE infection in C-84 boosted personnel.

Inclusion Criteria:

• At least 18 years old.
• VEE PRNT80 < 1:20 before immunization.
• (females) Negative urine pregnancy test on the same day before vaccination. Not planning pregnancy for 3 months.
• Actively enrolled in the SIP.
• At risk for exposure to virulent VEE virus (with up-to-date risk assessment).
• Previous TC-83 vaccination
• Up-to-date (within 1 year) physical examination/tests.
• Sign and date the approved informed consent.
• Willing to return for all follow-up visits.
• Agree to report adverse event (AE) up to 28 days after vaccination.

Exclusion Criteria:

• Over age of 65 years
• Clinically significant abnormal lab results including evidence of Hepatitis C, Hepatitis B carrier state, or elevated liver function tests.
• History of immunodeficiency or current treatment with immunosuppressive medication.
• (females) Currently breastfeeding.
• Confirmed human immunodeficiency virus (HIV) titer.
• Any known allergies to components of the vaccine.
• A medical condition that in the judgment of the Principal Investigator (PI) would impact subject safety (i.e-vaccination and or exposure to another alphavirus).
• Administration of any vaccine within 28 days of C-84.
• Any unresolved AEs resulting from a previous immunization.