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.