Immunogenicity and Safety of an Inactivated Rift Valley Fever Vaccine in a 19-Year Study
ARMY MEDICAL RESEARCH INST OF INFECTIOUS DISEASES FORT DETRICK MD
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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 PRNT80 or 140 to the primary series was observed in 90 of subjects. Estimate of the PRNT80 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 PRNT50 titer or 140, nearly all subjects 99.1 responded. In individuals not initially responding to the primary series PRNT80 140, 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 PRNT80 140 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.
- Medicine and Medical Research