This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The purpose of this research study is to compare reactions and antibody responses in subjects who are vaccinated with either a single dose of a standard flu vaccine or the experimental high dose vaccine. The experimental vaccine includes approximately four times the amount of each of three influenza virus proteins that are in the standard vaccine. Both the standard vaccine and the high dose vaccine contain the three influenza virus proteins that were recommended by the U.S. FDA for the 2004-2005 influenza season. The high dose influenza vaccine is considered investigational. Subjects will be in good general health, at least 65 years old, no allergies to eggs, no previous severe reactions to influenza vaccines, and not taking drugs or have underlying conditions that suppress the immune system. Primary Objectives: The immunogenicity endpoints to be evaluated by haemagglutination-inhibition assay (HAI) at 1 month post-vaccination are: 1) the proportion of subjects in each group who achieve a serum antibody titer of at least 1:32 (Baylor HAI assay) for each of the 3 vaccine antigens approximately 1 month after vaccination; 2) the geometric mean titer (GMT) of serum HAI antibody against each of the 3 vaccine antigens; 3) the rates of at least 4-fold increases in serum HAI antibody titer between pre-immunization and post-immunization serum samples; and 4) the proportion of subjects who achieve serum HAI antibody titers of 1:64 and 1:128 (Baylor HAI assay) for each of the 3 vaccine antigens approximately 1 month after vaccination. Secondary Objectives: The reactogenicity endpoints are the frequency and severity of solicited local and systemic adverse events (AE). The number and proportions of subjects in each group experiencing any injection site or systemic symptoms, and the proportions of subjects who experience moderate-to-severe symptoms will be determined for each vaccine.
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