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Randomized Controlled Trial
. 2012;7(12):e49704.
doi: 10.1371/journal.pone.0049704. Epub 2012 Dec 11.

A randomized clinical trial of an inactivated avian influenza A (H7N7) vaccine

Robert B Couch  1 , Shital M Patel, Chianti L Wade-Bowers, Diane Niño
Affiliations
Randomized Controlled Trial

A randomized clinical trial of an inactivated avian influenza A (H7N7) vaccine

Robert B Couch et al. PLoS One. 2012.

Abstract

Background: Concern for a pandemic caused by a newly emerged avian influenza A virus has led to clinical trials with candidate vaccines as preparation for such an event. Most trials have involved vaccines for influenza A (H5N1), A (H7N7) or A (H9N2).

Objective: To evaluate dosage-related safety and immunogenicity of an inactivated influenza A (H7N7) vaccine in humans.

Design: One hundred twenty-five healthy young adults were randomized to receive two doses intramuscularly of placebo or 7.5, 15, 45 or 90 µg of HA of an inactivated subunit influenza A (H7N7) vaccine (25 per group), four weeks apart. Reactogenicity was evaluated closely for one week and for any adverse effect for six months after each dose. Serum hemagglutination-inhibiting and neutralizing antibody responses were determined four weeks after each dose and at six months.

Results: Reactogenicity evaluations indicated the vaccinations were well tolerated. Only one subject developed a ≥4-fold serum hemagglutination-inhibition (HAI) antibody response and a final titer of ≥1:40 four weeks after dose two and only five subjects developed a neutralizing antibody rise and a final titer of ≥1:40 in tests performed at a central laboratory. Four of the five were given the 45 or 90 µg HA dosage. A more sensitive HAI assay at the study site revealed a dose-response with increasing HA dosage but only 36% in the 90 µg HA group developed a ≥4-fold rise in antibody in this test and only one of these achieved a titer of ≥1:32.

Conclusion: This inactivated subunit influenza A (H7N7) vaccine was safe but poorly immunogenic in humans.

Trials registration: ClinicalTrials.gov NCT00546585.

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Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist. The content of this publication does not necessarily reflect the views or policies of the Department of Health and Human Services, nor does mention of trade names, commercial products, or organizations imply endorsement by the U.S. Government.

Figures

Figure 1
Figure 1. Flow diagram of the randomized clinical trial of an inactivated subunit influenza A (H7N7) vaccine.
See this image and copyright information in PMC

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