Randomized, controlled trial of high-dose influenza vaccine among frail residents of long-term care facilities

Abstract

Background: Despite vaccination, residents of long-term-care facilities (LTCFs) remain at high risk of influenza-related morbidity and mortality. More-effective vaccine options for this population are needed.

Methods: We conducted a single-blinded, randomized, controlled trial comparing high-dose (HD) to standard-dose (SD) inactivated influenza vaccine (IIV) in 205 frail, elderly residents of LTCFs during the 2011-2012 and 2012-2013 influenza seasons. Hemagglutination inhibition (HI) antibody titers were measured at baseline and 30 and 180 days following vaccination.

Results: A total of 187 subjects (91%) completed the study. The mean age was 86.7 years. Geometric mean titers (GMTs) were significantly higher (P < .05) at day 30 for HD recipients, compared with SD recipients, for all comparisons except influenza A(H1N1) during 2012-2013 (the HD formulation was noninferior to the SD formulation for influenza A[H1N1] during 2012-2013). GMTs for HD and SD recipients during 2011-2012 were as follows: influenza A(H1N1), 78 (95% confidence interval [CI], 45-136) and 27 (95% CI, 17-44), respectively; influenza A(H3N2), 26 (95% CI, 17-40) and 10 (95% CI, 7-15), respectively; and influenza B, 26 (95% CI, 19-35) and 14 (95% CI, 11-18), respectively. During 2012-2013, GMTs for HD and SD recipients were as follows: influenza A(H1N1), 46 (95% CI, 33-63) and 50 (95% CI, 37-67); influenza A(H3N2), 23 (95% CI, 18-31) and 14 (95% CI, 11-18), respectively; and influenza B, 26 (95% CI, 21-32) and 17 (95% CI, 14-22), respectively. GMTs were significantly higher at day 180 for HD recipients, compared with SD recipients, for influenza A(H3N2) in both years (P < .001).

Conclusions: Among frail, elderly residents of LTCFs, HD influenza vaccine produced superior responses for all strains except influenza A(H1N1) in 2012-2013.

Clinical trials registration: NCT01654224.

Keywords: high-dose influenza vaccine; inactivated influenza vaccine; long-term care.

© The Author 2014. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Figures

Figure 1.

Consolidation Standards of Reporting Trials diagram of recruitment, enrollment, randomization, follow-up, and analyses.

Figure 2.

Reverse cumulative distribution of hemagglutination inhibition titers, by year and by strain, comparing high-dose and standard-dose influenza vaccines.