Fluzone High-Dose is an influenza vaccine designed specifically for people 65 years and older. Fluzone, Fluzone High-Dose, Fluzone Intradermal, and Fluzone Quadrivalent are all different types of flu vaccines produced by one manufacturer. Fluzone, Fluzone High-Dose, Fluzone Intradermal, and Fluzone Quadrivalent are all injectable influenza vaccines made to protect against the flu strains most likely to cause illness for that particular flu season. Fluzone High-Dose vaccine contains four times the amount of antigen that is in regular flu shots. The purpose of adding the additional antigen is to create a stronger immune response (more antibody) in the person who is receiving the vaccine.

Human immune defenses weaken with age, therefore older people are at a greater risk of suffering more severe illness from influenza. Aging also decreases the body's ability to have a positive immune response after getting the flu vaccine. A higher dose of antigen is supposed to give older people better protection against flu.

Data from clinical trials comparing Fluzone to Fluzone High-Dose among those 65 years or older reveal that a stronger immune response occurs after vaccination with the high-dose Fluzone. Research is currently being conducted to determine whether the improved immune response leads to greater protection.

For more information on the flu vaccine, visit this page on the CDC's website.