2773. Safety and Immunogenicity Study of Eastern Equine Encephalitis Vaccine

Abstract

BackgroundEastern equine encephalitis virus (EEEV) is an alphavirus with a high mortality rate and serious neurological sequelae in infected persons making this virus an important human pathogen.MethodsFollowing written informed consent, eligible subjects received two priming doses of EEEV vaccine, inactivated, TSI-GSD 104, 0.5 mL subcutaneously on days 0 and 28 days followed by a mandatory booster, 0.1 mL intradermal, at 6 months. Serum samples were collected pre-vaccination, days 21–35 following dose 2, as well as before and 21–35 days after dose 3. Sera with a Plaque Reduction Neutralization Test80 titer (PRNT80) ≥ 1:40 were considered responders with adequate titers for the purpose of biocontainment suite entry.ResultsSixty-seven (67) subjects were enrolled in this study to receive the primary vaccination series. All 67 subjects received at least 1 primary vaccination; 66 completed the 2 primary doses; 58 completed the 2 primary doses and the 6-month dose. Of these, 38 (56.7%) reported one or more adverse events. Fatigue was reported in 13 (19.4%), headache in 9 (13.4%), upper respiratory tract infection in 6 (9.0%), nausea in 5 (7.5%), pyrexia in 5 (7.5%), oropharyngeal pain in 4 (6.0%), myalgia in 4 (6.0%), injection site pain in 7 (10.4%), injection site hematoma in 4 (6.0%) and injection site erythema in 3 (4.5%) subjects. Adverse events were mostly mild or moderate and transient. PRNT80 titers ≥ 1:40 was observed in 39/65 (60%) subjects who received both primary doses of EEEV vaccine compared with 48/57 (84%) subjects who completed the 2-dose primary series and the 6-month dose and also had blood drawn for titer. Females had a higher response rate (61.5%) at the pre 6-month boost titer than did males (34.3%) (p = 0.0231). Similarly, the pre 6-month boost geometric mean titer (GMT) for females was 35.5 vs. 21.9 for males (p = 0.0231). The post 6-month boost GMT for females was 146.7 and 181.5 for males (P = 0.13).ConclusionInactivated Eastern Equine Encephalitis Virus vaccine, TSI-GSD 104, Lot 2-1-89 appears to be safe and immunogenic. This Phase 2 vaccine study supports a priming dose schedule of Days 0 and 28 and 6-month. The 6 month dose is anamnestic improving the overall response rate and level of antibody for this primary dosing schedule.Disclosures All authors: No reported disclosures.