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Ample evidence suggests that the influenza vaccine provides only limited protection to the people who need it the most — namely, older adults and chronically ill patients. In a manufacturer-supported multicenter phase III study, researchers evaluated whether higher doses of vaccine antigens would boost production of protective antibodies in an older population.
During the fall of 2006, nearly 4000 people (age, ≥65) were randomized to receive either the standard trivalent vaccine or an experimental vaccine that contained four times the standard amount of hemagglutinin (the major vaccine antigen) for each of the three included strains. Four weeks after vaccination, mean hemagglutinin titers were 70% to 80% higher for the two A strains in high-…