High-Dose Trivalent Flu Shot Better Protects Seniors

(HealthDay News) — A high-dose, trivalent, inactivated influenza vaccine (IIV3-HD) is associated with improved protection for seniors against laboratory-confirmed influenza infection compared with standard-dose trivalent, inactivated influenza vaccine (IIV3-SD), according to a study published in the August 14 issue of the New England Journal of Medicine.

Carlos A. DiazGranados, MD, from Sanofi Pasteur in Swiftwater, PA, and colleagues conducted a phase IIIb-IV randomized double-blind trial comparing IIV3-HD with IIV3-SD. Participants, aged ≥65 years, from 126 research centers, were randomized to receive IIV3-HD (15,991 participants) or IIV3-SD (15,998 participants).

The researchers found that 1.4% of participants in the IIV3-HD group and 1.9% in the IIV3-SD group had laboratory-confirmed influenza caused by any viral type or subtype that was associated with a protocol-defined influenza-like illness (relative efficacy, 24.2%). During the safety surveillance period, 8.3% of participants in the IIV3-HD group and 9.0% in the IIV3-SD group had at least one serious adverse event (relative risk, 0.92; 95% confidence interval, 0.85–0.99). In the IIV3-HD group, hemagglutination-inhibition titers and seroprotection rates were significantly higher after vaccination.

“Among persons ≥65 years of age, IIV3-HD induced significantly higher antibody responses and provided better protection against laboratory-confirmed influenza illness than did IIV3-SD,” the authors write.

The study was funded by Sanofi Pasteur.

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