Safety and immunogenicity of an inactivated eastern equine encephalitis virus vaccine

Eastern equine encephalitis virus (EEEV) is a mosquito borne alphavirus spread primarily in Atlantic and Gulf Coast regions of the United States. EEEV is the causative agent of a devastating meningoencephalitis syndrome, with approximately 30% mortality and significant morbidity. There is no licensed human vaccine against EEEV. An inactivated EEEV vaccine has been offered under investigational new drug (IND) protocols at the United States Army Medical Research Institute of Infectious Diseases (USAMRIID) since 1976. Healthy at-risk laboratory personnel received inactivated PE-6 strain EEEV (TSI-GSD 104) vaccine under two separate IND protocols. Protocol FY 99–11 (2002–2008) had a primary series consisting of doses on day 0, 7, and 28. Protocol FY 06–31 (2008–2016) utilized a primary series with doses on day 0 and 28, and month 6. Participants with an inadequate immune response, plaque reduction neutralization test with 80% cut-off (PRNT80) titer