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Volume 13, Number 5—May 2007


Inactivated Whole Virus Influenza A (H5N1) Vaccine1

Zoltan Vajo*Comments to Author , Lajos Kosa*, Ildiko Visontay†, Mate Jankovics‡, and Istvan Jankovics†
Author affiliations: *National Center for Allergy and Immunology, Budapest, Hungary;; †National Center for Epidemiology, Budapest, Hungary; and; ‡Semmelweis University Medical School, Budapest, Hungary;

Main Article


Immunogenicity findings of whole-virus influenza vaccine trial, Hungary*†

CHMP‡ requirement‡ Total study population Male Female
Day 21
GMT NA 27.9 31.0 25.6
Post- to pre-vaccination GMT ratio (increase) >2.5 5.6‡ 6.2‡ 5.1‡
% of participants seropositive (titer >1:40) >70 63.7 70.8‡ 58.0
% of participants with seroconversion (4-fold titer
increase or titer >1:40) >40 63.7* 70.8‡ 58*
Day 90
GMT NA 29.4 31.9 27.4
Post- to pre-vaccination GMT ratio (increase) >2.5 5.9‡ 6.4‡ 5.5‡
% of participants seropositive (titer >1:40) >70 6.3 73.9‡ 61.8
% of participants with seroconversion (4-fold titer
increase or titer >1:40) >40 67.3‡ 73.9* 61.8‡

*CHMP, Committee for Medicinal Products for Human Use, European Medicines Agency; GMT, geometric mean titer; NA, not applicable.
†Hemagglutination-inhibition (HI) titers below the limit of detection were given an arbitrary value of 1:5. GMTs of antibody and their confidence intervals were computed by transforming the results to a logarithmic scale, assuming asymptotic normality conditions were satisfied on the scale and converting back to the original scale. HI endpoints were the GMT at each timepoint and the variables required for interpandemic influenza vaccines: postvaccination seropositivity rate (% of participants with titers ≥40), the post- to pre-vaccination GMT ratio, and the proportion of persons seroconverting or displaying a 4-fold titer increase postvaccination.:
‡Met CHMP standards.

Main Article

1The study design has been presented as an oral presentation at the World Health Organization Meeting on Evaluation of Pandemic Influenza Vaccines in Clinical Trials, May 4–5, 2006, Geneva, Switzerland.

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