title: Immunogenicity and safety of an inactivated Rift Valley fever vaccine in a 19-year study.
abstract: An investigational, formalin-inactivated Rift Valley fever (RVF) vaccine, known as The Salk Institute-Government Services Division (TSI-GSD) 200 vaccine, was administered to 1860 at-risk subjects (5954 doses) between 1986 and 2004 as a three-dose primary series (days 0, 7, and 28) followed by booster doses as needed for declining titers. An initial positive serological response (PRNT(80)≥1:40) to the primary series was observed in 90% of subjects. Estimate of the PRNT(80) response half-life in initial responders to the primary series by Kaplan-Meier plot was 315 days after the primary series dose 3. Differences in a serological response were observed at 2 weeks after dose 3 of the primary series between vaccine lots and for gender (women>men); a trend was observed for age (<40 years). When response to the primary series was measured by PRNT(50) titer ≥1:40, nearly all subjects (99.1%) responded. In individuals not initially responding to the primary series (PRNT(80)<1:40), a response was observed in most subjects after receiving only one booster dose. Immune response (all subjects) to subsequent booster doses for a declining titer (PRNT(80)<1:40) was 98.4%. The vaccine was well-tolerated; vaccine-related adverse reactions were generally mild and self-limited. Differences in adverse events were observed with vaccine lot and sex. The data support the safety and immunogenicity of the inactivated RVF vaccine, and may serve as a standard of comparison for immunogenicity and safety for future RVF vaccines.
authors.affiliation: Clinical Research Management, Inc., Special Immunizations Program, United States Army Medical Research Institute of Infectious Diseases, 1425 Porter Street, Fort Detrick, MD 21702, United States. Janice.Rusnak@amedd.army.mil
authors.forename: Janice M
authors.initials: JM
authors.lastname: Rusnak
authors.forename: Paul
authors.initials: P
authors.lastname: Gibbs
authors.forename: Ellen
authors.initials: E
authors.lastname: Boudreau
authors.forename: Denise P
authors.initials: DP
authors.lastname: Clizbe
authors.forename: Phillip
authors.initials: P
authors.lastname: Pittman
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000914:Antibodies, Viral / Q000097:blood; D005260:Female; D006801:Humans; D007114:Immunization / Q000379:methods; D007117:Immunization, Secondary / Q000379:methods; D008297:Male; D008875:Middle Aged; D012295:Rift Valley Fever / Q000276:immunology / Q000517:prevention & control*; D012296:Rift Valley fever virus / Q000276:immunology*; D015164:Vaccines, Inactivated / Q000008:administration & dosage / Q000009:adverse effects / Q000276:immunology; D014765:Viral Vaccines / Q000008:administration & dosage / Q000009:adverse effects / Q000276:immunology*; D055815:Young Adult
chemical_list: D000914:Antibodies, Viral; D015164:Vaccines, Inactivated; D014765:Viral Vaccines