H9 Priming Study in Healthy Adults

Influenza Clinical Trial

Official title: A Randomized, Double-Blind, Clinical Trial Evaluating the Immunogenicity of an Inactivated Influenza A/H9N2 Vaccine Among Healthy Adults With and Without Prior Exposure to Influenza A/H2N2

Status Completed

Clinical Trial Summary

The purpose of this research study is to determine whether prior exposure to A/H2N2 viruses is associated with better antibody (part of the immune system that fights infection) responses after vaccination with an A/H9N2 flu vaccine. The study will evaluate how much antibody is made to the influenza virus after H9N2 flu vaccination and how the body reacts to different strengths of the H9N2 flu vaccine. This information may guide vaccine development for this virus as well as other bird flu viruses that have infected humans. Study participants will include 120 healthy subjects, age 18-38 or 44-59 years. Two different dosages of vaccine will be given in the muscle of the upper arm about 1 month apart. The assignment of vaccines to participants is governed by chance. Study procedures may include medical history, physical exam, and blood samples. Study participation duration is about 7 months.

Clinical Trial Description

Influenza A viruses have the potential to cause worldwide epidemics and/or pandemics resulting in significant morbidity and mortality. The goals of this study are to determine whether persons over 44 years of age (born before 1964) have evidence of priming to influenza A/H9N2 viruses as measured by responses to two different dosage levels of an A/H9N2 vaccine. Evidence of priming for persons born before 1964 has implications in pandemic preparedness planning in that such individuals may need only a single vaccination to induce immunity compared to persons who are not immunologically primed. This study will also explore the immunogenicity of two-dose regimen using a homologous A/H9N2 virus as an antigen for the hemagglutination inhibition assay (HAI) and neutralizing antibody assays. Approximately 120 healthy adults will be enrolled into this single-center, randomized, double-blind trial of subvirion inactivated influenza A/H9N2 (G9 variant) vaccine given by intramuscular (IM) injection. Subjects will be stratified by age, with 50 percent in each dosage group being between the ages of 18 and 38 inclusive and the other 50 percent being between the ages of 44 and 59 years, inclusive. Subjects will be randomized 1:1 to receive 2 doses one month apart of one of two dosages (7.5 micrograms or 30 micrograms) of A/chicken/Hong Kong/G9/97 subvirion vaccine. The subjects and staff responsible for assessing responses after vaccination will be blinded to the dosage level that is administered. All subjects will receive two doses of their assigned dosage level given by the IM route separated by approximately 28 days. Subjects will be observed in the clinic for approximately 20 minutes after vaccination. Subjects will maintain a memory aid recording oral temperature, and systemic and local adverse events for 7 days after each inoculation. They will return to clinic on day 8 after vaccination (window 8-10) for adverse event (AE) assessment, concomitant medication assessment, a targeted physical exam (if indicated), and review of memory aid. AE data will be captured Day 0 through Day 56. Serious adverse event (SAE) data will be captured from Day 0 through the end of the trial (7 months after the first dose of vaccine). Serum for immunogenicity evaluations will be obtained prior to the first vaccination, at Day 0, prior to the second vaccination, at Day 28 and at Day 56. The primary objective is to determine whether persons 44-59 years of age show evidence of immunologic priming to A/H9 virus compared to persons 18-38 years of age. The secondary objectives are to evaluate dose-related immunogenicity 4 weeks after each vaccination and to evaluate the safety and tolerability of the vaccine. ;

Study Design

Allocation: Randomized, Endpoint Classification: Safety/Efficacy Study, Intervention Model: Parallel Assignment, Masking: Double Blind (Subject, Investigator, Outcomes Assessor), Primary Purpose: Prevention

Related Conditions & MeSH terms

• Influenza
• Influenza, Human

• NCT number: NCT00617331
• Study type: Interventional
• Source: National Institute of Allergy and Infectious Diseases (NIAID)
• Status: Completed
• Phase: Phase 2
• Start date: February 2008
• Completion date: January 2009