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Older individuals are at high risk for complications from influenza; they are also more likely to have low antibody responses to influenza vaccines. Researchers randomized 202 elders (mean age, 72; 41% women) to one of four inactivated influenza vaccine doses (0, 15, 30, or 60 μg hemagglutinin for each of three strains). Antibody titers were obtained at baseline and at 1 month. Adverse effects were assessed for 6 months after vaccination.
Researchers found a dose-related increase in mean antibody titers and in the percentage of participants with protective titers (hemagglutination inhibition titer, ≥32). Increases in the frequency of localized reactions (i.e., redness and swelling) also were found with increasing doses; however, most reactio…