High-dose trivalent influenza vaccine: safety and immunogenicity

Adults aged 65 years or older suffer the most severe health effects of seasonal flu. Although the influenza vaccine is effective in preventing influenza virus infection and its complications, it is not as effective in the elderly due to age-associated immunosenescence phenomenon. Since 2009, a high-dose trivalent influenza vaccine has been approved in the United States for the immunization of people >= 65 years with an antigen concentration four times higher than the standard vaccine. Multiple clinical trials carried out over different seasons, and using different methodologies, have shown that the high-dose trivalent influenza vaccine is not only more effective, but it also has a similar safety profile and is more immunogenic than the standard dose vaccine in the prevention of flu and its complications in the elderly. This document reviews the current scientific evidence on the safety and immunogenicity of high-dose influenza vaccine in people aged 65 years and over, and includes information from randomized clinical trials, observational studies with data from real clinical practice, and systematic reviews, and meta-analysis.