713. Long-term and Cross-reactive Immunogenicity of Inactivated Trivalent Influenza Vaccine in the Elderly: MF59 Adjuvanted Vaccine Versus Unadjuvanted Vaccine
Session: Poster Abstract Session: Vaccine Studies, Adjuvants, and Discovery
Friday, October 21, 2011
Room: Poster Hall B1
Background: Due to their high risk for serious complications from influenza, the elderly have been considered as the priority group for influenza vaccination. However, influenza vaccine-induced antibody was believed to decline more rapidly in the elderly.

Methods: During early 2009-2010 influenza season, this study was designed to evaluate and compare the long-term immunogenicity and cross-reactive immunogenicity for two seasonal trivalent influenza vaccines, one with MF59 adjuvant and one without an adjuvant. Serum hemagglutinin inhibition (HI) titers for three seasonal vaccine strains were determined pre-vaccination, at 1 month post-vaccination and 6 months post-vaccination. In addition, cross-reactive immunogenicity was evaluated for 2009 pandemic influenza A/H1N1 (A/California/7/2009) at 1 month post-vaccination.

 Results: Of the 100 subjects, 95 (95%) and 76 (76%) subjects were followed up during 1-month and 6-month post-vaccination period. Both MF59-adjuvanted and unadjuvanted vaccine met the EMA criteria for all three vaccine strains at 1 month after vaccination, but seroprotection for influenza B was not satisfactory with the rates of 55.3% (MF59 adjuvanted vaccine) and 47.9% (unadjuvanted vaccine). At six months post-vaccination, seroprotection rates for all three strains had declined significantly irrespective of vaccine formulation (p < 0.01), but MF59-adjuvanted vaccine showed higher seroprotection rate and still met the EMA criteria for A/H1N1 (62.5% vs. 55.5%) and A/H3N2 (72.5% vs. 47.2%) compared to unadjuvanted vaccine. Both MF59 adjuvanted and unadjuvanted influenza vaccine did not show cross-reactive immunogenicity for 2009 pandemic influenza A; seroprotection rates were 16.7% and 14.9% respectively.

Conclusion: MF59 adjuvanted influenza vaccine showed superior long-term immunogenicity compared to unadjuvanted vaccine in the elderly. Cross-reactive immunogenicity was not induced.

Subject Category: I. Adult and Pediatric Vaccines

Joon Young Song, MD1,2, Hee Jin Cheong, MD1,2, Ji Yun Noh, MD1, Jung Yeon Heo, MD3, Yu Bin Seo1, In Sun Kim1, Won Suk Choi, MD4 and Woo Joo Kim, MD2,5, (1)Department of Internal Medicine, Korea University College of Medicine, Seoul, South Korea, (2)Korea University Guro Hospital, Seoul, Korea, Republic of, (3)Armed Forces Capital Hospital, Boondang, South Korea, (4)Korea University Ansan Hospital, Ansan, South Korea, (5)Korea University, Seoul, South Korea


J. Y. Song, None

H. J. Cheong, None

J. Y. Noh, None

J. Y. Heo, None

Y. B. Seo, None

I. S. Kim, None

W. S. Choi, None

W. J. Kim, None

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