The UK study (Study 2) was a randomized, controlled study that enrolled 275 healthy subjects ages 65 years and older. This study compared AFLURIA® with a European-licensed trivalent inactivated influenza vaccine as an active control. The evaluable efficacy population consisted of 274 subjects (206 in the AFLURIA® group and 68 in the control group). Among these subjects, 50% were men and 50% were women, with a mean age of 72 years (range: 65 to 93 years).

The co-primary immunogenicity endpoints for the seroconversion rate and the proportion of subjects with a minimum post-vaccination HI antibody titer of 1:40 are presented in Table 4.

Table 4: Study 2 - Serum HI Antibody Responses in Subjects ≥ 65 Years Receiving AFLURIA®

A second UK study (Study 3) was a randomized, controlled study that enrolled 406 healthy subjects ages 18 years and older (stratified by age from 18 to less than 60 years and 60 years and older). This study compared AFLURIA® with a European-licensed trivalent inactivated influenza vaccine as an active control. In a post-hoc analysis of different age ranges, among subjects ages 18 to less than 65 years receiving AFLURIA® (146 subjects), 47% were men and 53% were women, with a mean age of 48 years for all subjects. Among subjects ages 65 years and older receiving AFLURIA® (60 subjects), 53% were men and 47% were women, with a mean age of 71 years.

The post-hoc analysis of serum HI antibody responses showed that the lower bound of the 95% CI for subjects with HI antibody titers of 1:40 or greater after vaccination exceeded 70% for each strain. HI antibody responses were lower in subjects ages 65 years and older after administration of AFLURIA®. Serum HI antibody responses to the active control were similar to those for AFLURIA® in both age groups.

REFERENCES

1. Hannoun C, Megas F, Piercy J. Immunogenicity and protective efficacy of influenza vaccination. Virus Res 2004;103:133-138.

2. Hobson D, Curry RL, Beare AS, et al. The role of serum hemagglutination-inhibiting antibody in protection against challenge infection with influenza A2 and B viruses. J Hyg Camb 1972;70:767-777.

3. Centers for Disease Control and Prevention. Prevention and Control of Influenza: Recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR Recomm Rep 2007;56 (RR-6):1-53.

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