A 2013/2014 northern hemisphere season surface antigen inactivated trivalent influenza vaccine - Assessing the immunogenicity and safety in an open label, uncontrolled study

The present study evaluated the safety and immunogenicity of the 2013/2014 trivalent surface antigen inactivated subunit seasonal influenza virus vaccine Fluvirin® in healthy adults (18 - ≤ 60 years) and elderly (>60 years). The vaccine contained 15 µg haemagglutinin protein from each of influenza A/California/7/2009 (H1N1)pdm09-like strain, A/Victoria/361/2011 (H3N2)-like strain and B/Massachusetts/2/2012-like strain (B/Yamagata) as recommended by the WHO in the 2013/2014 Northern Hemisphere season. Antibody response to each influenza antigen after vaccination was measured prior to vaccination and 21 d after by single radial hemolysis (SRH) assay or hemagglutination inhibition (HI) assay in accordance with Guidance CPMP/BWP/214/96. 125 subjects (61 adults and 64 elderly) were enrolled in the study. Pre-vaccination protective antibody levels (SRH area ≥ 25 mm(2)) against A(H1N1), A(H3N2) and the B strain were detected in 17%, 20% and 57% of adults and in 36%, 20% and 55% of elderly, respectively, Post-vaccination, SRH area ≥ 25 mm(2) was detectable in 95%, 82% and 92% in adult and in 80%, 84% and 92% of the elderly subjects for A(H1N1), A(H3N2) and the B strain, respectively. Geometric mean ratio (GMR) was higher in adult subjects (2.62-7.62) than in elderly subjects (2.33-3.42). All three CHMP licensure criteria were met for all strains contained in the vaccine for both age groups. The most frequently reported solicited local and systemic reactions were pain at the injection side, headache and fatigue. In conclusion, the vaccine demonstrated a good immunogenicity and an acceptable safety profile in both adults and elderly.