Phase II, dose ranging study of the safety and immunogenicity of single dose West Nile vaccine in healthy adults ≥ 50 years of age.

Abstract

INTRODUCTION:

ChimeriVax-WN02 is a live, attenuated chimeric vaccine for protection against West Nile virus (WNV) produced by insertion of the genes encoding the pre-membrane (prM) and envelope (E) proteins of WNV (strain NY99) into the yellow fever 7D vaccine virus. This Phase II, randomized, double-blind, placebo-controlled, multi-center study in the US assessed the immunogenicity, viremia, and safety of the ChimeriVax-WN02 vaccine.

METHODS:

The study included adults in general good health. Subjects aged ≥ 50 years were randomized to one of four treatment groups: ChimeriVax-WN02 4 × 10(3) plaque-forming units (pfu) (n=122), 4 × 10(4)pfu (n=124), 4 × 10(5)pfu (n=113), or placebo (n=120). A subset of subjects was randomized to assess viremia after vaccination at three different dose levels. Subjects were followed for safety up to 6 months after vaccination.

RESULTS:

A total of 121 subjects for WN024 × 10(3), 122 for WN02 4 × 10(4), 110 for WN02 4 × 10(5), and 120 for the placebo group completed the study up to the 6-month safety follow-up. Seroconversion, as measured by plaque reduction neutralization test (PRNT), was achieved at Day 28 by 92.1%, 93.2%, and 95.4% of subjects in the WN02 4 × 10(3), the WN02 4 × 10(4), and the WN02 4 × 10(5) groups, respectively. Viremia was transient, detected between Days 2 and 14 but not at Day 28, and in most cases did not reach the quantification threshold. The percentage of subjects reporting at least one event of reactogenicity was similar in the placebo and active vaccine groups and showed no dose relationship.

CONCLUSIONS:

The ChimeriVax-WN02 vaccine was highly immunogenic and well tolerated among subjects ≥ 50 years old at all dose levels.

• Authors: Gustavo H Dayan, Joan Bevilacqua, Dorothy Coleman, Aileen Buldo, George Risi
• Journal: Vaccine (Vaccine) Vol. 30 Issue 47 Pg. 6656-64 (Oct 19 2012) ISSN: 1873-2518 [Electronic] Netherlands
• PMID: 22959989 (Publication Type: Clinical Trial, Phase II, Journal Article, Multicenter Study, Randomized Controlled Trial, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2012 Elsevier Ltd. All rights reserved.

Chemical References

• Antibodies, Neutralizing
• Antibodies, Viral
• ChimeriVax
• Vaccines, Attenuated
• West Nile Virus Vaccines

Topics

• Aged
• Animals
• Antibodies, Neutralizing (blood)
• Antibodies, Viral (blood)
• Chlorocebus aethiops
• Double-Blind Method
• Female
• Humans
• Male
• Middle Aged
• Neutralization Tests
• United States
• Vaccines, Attenuated (administration & dosage, adverse effects, immunology)
• Vero Cells
• Viral Plaque Assay
• Viremia (pathology)
• West Nile Virus Vaccines (administration & dosage, adverse effects, immunology)
• West Nile virus (immunology, pathogenicity)
• Yellow fever virus (immunology)