576b. Randomized Clinical Trial of High-Dose Influenza Vaccine in Nursing Home Residents
Session: Oral Abstract Session: Featured Oral Abstract
Thursday, October 3, 2013: 4:45 PM
Room: The Moscone Center: Esplanade Ballroom 301-310
Background: Each year in the US 3,000-49,000 influenza-associated deaths occur, with over 90% reported among adults aged ≥65 years. Influenza also results in an estimated 226,000 hospitalizations annually, with hospitalization rates among older adults increasing over the past two decades. More effective vaccine options are needed for frail older adults. This study (NCT01654224) assessed the non-inferiority and superiority of high-dose (HD) versus standard-dose (SD) inactivated influenza vaccine among nursing home residents.

Method: This clinical trial was conducted during the 2011-12 and 2012-13 influenza seasons. At baseline, 205 eligible consented subjects provided a venous blood sample for hemagglutination inhibition (HI) titers and randomly received SD or HD inactivated influenza vaccine.  One month later, blood sampling was repeated. Geometric mean titers (GMTs) and 2-sided 95% confidence intervals (CIs) were calculated. An upper bound <1.5 of the 2-sided 95% CI on the ratio of post-vaccination GMTSD to GMTHD indicated non-inferiority. A lower bound ≥1.0 of the 2-sided 95% CI on the ratio of GMTHD to GMTSD indicated superiority. Non-inferiority and superiority tests were performed separately for the 2011-12 and 2012-13 vaccine formulations because the vaccines contained different A/H3N2 and B strains.

Result: The completion rate was 82.4% (169/205), including 56 participants in 2011-12 and 113 participants in 2012-13; 34 subjects participated both years. Mean age of participants was 86.7 years; 71% were ≥85 years. Most participants were white (99%) and female (68%). Demographic profiles of both groups were similar. HD vaccine produced GMT responses to the A/H1N1, A/H3N2, and B strains that were non-inferior to those induced by SD vaccine during both influenza seasons; moreover, HD vaccine induced superior antibody responses to all three strains in 2011-12, and to the A/H3N2 and B strains in 2012-13.

Conclusion: HD influenza vaccine produces non-inferior HI titer responses for A/H1N1, A/H3N2, and B strains among frail elderly nursing home residents. Superiority of HD influenza vaccine was demonstrated for all strains except A/H1N1 in 2012-13, perhaps because 30% of subjects (34/113) participated in both seasons when the A/H1N1 strains were identical.

Richard K. Zimmerman, MD MPH1, Chyongchiou Jeng Lin, PhD1, Ted Ross, PhD2, Stacey Saracco, RN3 and David Nace, MD, MPH4, (1)Family Medicine, University of Pittsburgh, Pittsburgh, PA, (2)Vaccine & Gene Therapy Institute of Florida, Port Saint Lucie, FL, (3)Division Of Geriatric Medicine, University of Pittsburgh, Pittsburgh, PA, (4)Division of Geriatric Medicine, University of Pittsburgh, Pittsburgh, PA

Disclosures:

R. K. Zimmerman, Sanofi: Grant Investigator, Research grant

C. J. Lin, Sanofi: Grant Investigator, Research grant

T. Ross, None

S. Saracco, None

D. Nace, Sanofi Pasteur: Grant Investigator, Research grant

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