542. Influenza Immunization in Older Adults: Impact of Frailty
Session: Poster Abstract Session: Influenza Vaccines
Friday, October 21, 2011
Room: Poster Hall B1
Handouts
  • 542_SeanLeng.pdf (8.6 MB)
  • Background: 

    While annual immunization with a trivalent inactivated vaccine (TIV) has been shown efficacious, recent data suggest a selection bias towards nonfrail or healthy seniors in prior retrospective TIV studies. This study aimed to evaluate potential impact of frailty, an important geriatric syndrome, on TIV-induced antibody response and its clinical effectiveness.

    Methods: 

    This is a prospective observational study performed during 2007-2008 season. Frailty status was determined by the validated 5-item criteria: weakness (grip strength), slowed walking speed, weight loss, low physical activity and exhaustion. Subjects with 3 or more items were categorized as frail, those with 1-2 items as prefrail, and those with none as nonfrail. All subjects were given a standard TIV and monitored for influenza-like illness (ILI) during post-vaccination season. Blood samples were collected pre- and 3-4 weeks post-vaccination, and 3-4 weeks post-ILI (from those who developed ILI). Pre- and post-vaccination and post-ILI strain-specific anti-influenza antibody titers against hemagglutinin were measured using standard hemagglutination inhibition (HI) assay. Geometric mean of HI titers (GMT), GMT ratios and rates of post-vaccination ILI and serology-confirmed influenza infection were compared between the frailty groups.

    Results: 

    A total of 71 subjects completed the study (mean age 84.5, range 72-95 yrs). Post-vaccination GMTs as well as GMT ratios had significant stepwise decrease from the nonfrail (n=22) and prefrail (n=32) to the frail subjects (n=17) adjusted for age (GMT ratios: 1.6, 1.3, 1.1, respectively, to H1N1, p= .04; 1.9, 1.6, 1.1, to H3N2, p= .01; and 1.5, 1.3, 1.1, to B, p= .05). Rates of ILI and confirmed influenza infection had significant stepwise increase from the nonfrail and prefrail to the frail participants adjusted for age (9%, 25%, and 53%, respectively, p= .005 for ILI; 5%, 16%, and 29%, respectively, p= .03 for influenza infection).

    Conclusion: Our data indicate significant impact of frailty on TIV-induced antibody response and clinical protection in older adults. They suggest that assessing frailty status in the elderly may identify those who are less likely to respond to TIV immunization and be at higher risk for seasonal influenza.  


    Subject Category: I. Adult and Pediatric Vaccines

    Xu Yao, MD1, Robert Hamilton, PhD1 and Sean Leng, MD, PhD2, (1)Medicine/Allergy & Clinical Immunology, Johns Hopkins University School of Medicine, Baltimore, MD, (2)Medicine/Geriatrics, Johns Hopkins University School of Medicine, Baltimore, MD

    Disclosures:

    X. Yao, None

    R. Hamilton, None

    S. Leng, None

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