Phase II, randomized, double-blind, placebo-controlled, multicenter study to investigate the immunogenicity and safety of a West Nile virus vaccine in healthy adults.

BACKGROUND: ChimeriVax-WN02 is a live, attenuated chimeric vaccine for protection against West Nile virus. This Phase II, randomized, double-blind, placebo-controlled, multicenter study assessed the immunogenicity, viremia, and safety of the ChimeriVax-WN02 vaccine. METHODS: The 2-part study included adults in general good health. In part 1, subjects aged 18-40 years were randomized to 1 of 4 treatment groups: ChimeriVax-WN02 3.7- × -10(5) plaque-forming units (PFU), 3.7 × 10(4) PFU, 3.7 × 10(3) PFU, or placebo. In part 2, subjects aged 41-64 and ≥ 65 years were randomized to receive ChimeriVax-WN02 3.7 × 10(5) PFU or placebo. RESULTS: In both part 1 and part 2, seroconversion was achieved at day 28 by >96% of subjects in active treatment groups. In part 1, neutralizing antibody titers at day 28 were higher and viremia levels lower with the highest dose, whereas the adverse event profile was similar between the dose groups. In part 2, antibody titers and viremia levels were higher in subjects aged ≥ 65 years, and more subjects in the 41-64 years cohort experienced adverse events. CONCLUSIONS: The ChimeriVax-WN02 vaccine was highly immunogenic in younger adults and the elderly, and it was well tolerated at all dose levels and in all age groups investigated. Clinical Trials.gov identifier: NCT00442169.

Vaccinations for the Older Adult.

Vaccine response declines with age, but currently recommended vaccines are safe and effective in reducing, if not preventing, disease altogether. Over the last decade, advancements in vaccine immunogenicity, either by increasing dose or conjugating vaccines to protein, have resulted in more immunogenic vaccines that also seem more effective in reducing clinical disease both for influenza and pneumococcus. Meanwhile, there is a resurgence in incident pertussis, exceeding prevalence from five decades ago, adding older adults to a recommended target vaccination group. This article discusses currently available vaccines, in the context of current epidemiology and recommendations, for older adults.

Safety and immunogenicity of a quadrivalent inactivated influenza vaccine compared to licensed trivalent inactivated influenza vaccines in adults.

PURPOSE: To evaluate the safety and immunogenicity of a prototype quadrivalent inactivated influenza vaccine (QIV) containing two influenza B strains, one of each lineage, compared with licensed trivalent inactivated influenza vaccines (TIVs) containing either a Victoria B-lineage strain (2009-2010 TIV) or a Yamagata B-lineage strain (2008-2009 TIV). METHODS: Healthy adults ≥18 years of age were eligible to participate in this phase II, open-label, randomized, controlled, multicenter study conducted in the US. Participants received a single dose of 2009-2010 TIV, 2008-2009 TIV, or QIV. Sera were collected before and 21 days after vaccine administration to test for hemagglutination inhibition (HAI) antibodies to each of the four influenza strains. Immunogenicity endpoints included geometric mean HAI antibody titers (GMTs) and rates of seroprotection (titer ≥1:40) and seroconversion (4-fold rise pre- to post-vaccination). Safety endpoints included frequency of solicited injection-site and systemic reactions occurring within 3 days of vaccination, and unsolicited non-serious adverse events (AEs) and serious AEs (SAEs) within 21 days of vaccination. RESULTS: One hundred and ninety participants were enrolled to each vaccine group. QIV induced GMTs to each A and B strain that were noninferior to those induced by the 2009-2010 and 2008-2009 TIVs (i.e., lower limit of the two-sided 95% confidence interval of the ratio of GMT(QIV)/GMT(TIV)>0.66 for each strain). Rates of seroprotection and seroconversion were similar in all groups. Incidence and severity of solicited injection-site and systemic reactions, AEs, and SAEs were similar among groups. CONCLUSION: QIV, containing two B strains (one from each B lineage), was as safe and immunogenic as licensed TIV. QIV has the potential to be a useful alternative to TIV and offer protection against both B lineages.