Scientic-production association "Microgen" has finished 1st phase of clinical trials of candidate
vaccines against
avian influenza in order to assess their reactogenicity, safety, and immunogenicity. Two
vaccines constructed from NIBRG-14
vaccine strain [A/Vietnam/1 194/2004 (H5N1)], obtained from World Health Organization, were studied: "OrniFlu" (inactivated subunit
influenza vaccine adsorbed on
aluminium hydroxide) and inactivated
polymer-subunit
influenza vaccine with
polyoxydonium (IPSIV). Clinical trial of the
vaccines with different quantity of
antigen (15, 30, and 45 mcg of H5N1 virus
hemagglutinin) was carried out in
Influenza Research Institute (St. Petersburg) and in Mechnikov Research Institute of
Vaccines and Sera (Moscow). Analysis of results allowed to conclude that both
vaccines were safe, well tolerated and characterized by low reactogenicity. Two-doses vaccination schedule was needed to meet required seroconversion and seroprotection rates (> or =1:40 in > or =70% of vaccinated volunteers). "Orni-
Flu" vaccine containing 15 mcg of
hemagglutinin and optimal quantity of
aluminium hydroxide (0.5 mg) in one dose as well as IPSIV containing 45 mcg of
hemagglutinin and 0.75 mg of
polyoxydonium in one dose were most immunogenic after 2 doses - seroprotection rates in microneutralization assay were 72.2% and 77.0% respectively. Marked influence of
aluminium hydroxide content on immunogenicity of the "OrniFlu"
vaccine was confirmed in the study. Optimal quantity of adjuvant was 0.5 mg per dose. According to basic concept of
vaccine development, preference is given to
vaccine that under minimal quantity of
antigen induces sufficient specific immune response and is safe in volunteers. "OrniFlu"
vaccine containing 15 mcg of H5N1 virus
hemagglutinin and optimal quantity of
aluminium hydroxide (0.5 mg) corresponded to these requirements that allowed researchers to recommend it for clinical trials of 2nd phase.