Exercise, aging, stress, and the efficacy of the influenza vaccine

The elderly population may experience a decline in their immune function that may impair influenza vaccine efficacy. Regular exercise may lead to an increase in the immune function, whereas psychological stress may decrease the immune response. The purpose of this study was to determine whether exercise and psychological stress are related to immunity in an elderly population (60+ yrs. old) given the influenza vaccine. Participants (n=55) were vaccinated with the 1999 influenza vaccine and blood was drawn 14-days post vaccine. The participants were divided into three exercise groups: active, moderately active, and sedentary. Psychosocial factors were assessed using the Life Orientation Test (LOT), the Perceived Stress Scale (PSS), and a social activity survey. Exercise levels were assessed using a modification of the Yale Physical Activity Survey. Enzyme-linked immunosorbent assays (ELISAs) were used to measure the following parameters: IL-2, IL-4, IL-10, IL-12, and IFN-γ. The results from ANOVA and regression analyses showed that sedentary individuals had less influenza specific proliferation than active or moderately active individuals whereas active individuals had a greater antibody titer than moderately active or sedentary individuals. IL-2 production, T-helper and T-cytotoxic cells all were influenced by gender. PSS was a significant predictor of IL-2 and IgG antibody titer. Greater activity levels were associated with reduced perceived stress. The psychosocial measures of LOT and IL-10 production influenced immunity. The elderly population is more susceptible to infections, due to the decrease in their immune system. These findings suggest that activity and psychosocial factors dependent of activity influence immune response to influenza immunization in older adults