Better influenza vaccines for older people: what will it take?

JE McElhaney, JP Dutz - The Journal of infectious diseases, 2008 - academic.oup.com
The Journal of infectious diseases, 2008academic.oup.com
Of all infectious diseases, influenza is foremost in its association with an agerelated increase
in serious consequences leading to hospitalization, debilitating complications, and death.
Current influenza vaccines are both effective [1] and cost saving [2]; however, in spite of
widespread influenza vaccination programs, rates of hospitalization for acute respiratory
illnesses and cardiovascular diseases have been increasing in the population aged 65
years during the influenza season [3]. Given that current influenza vaccines are only 30 …
Of all infectious diseases, influenza is foremost in its association with an agerelated increase in serious consequences leading to hospitalization, debilitating complications, and death. Current influenza vaccines are both effective [1] and cost saving [2]; however, in spite of widespread influenza vaccination programs, rates of hospitalization for acute respiratory illnesses and cardiovascular diseases have been increasing in the population aged 65 years during the influenza season [3]. Given that current influenza vaccines are only 30%–40% effective in this population, there appears to be a considerable margin for improvement. However, in spite of recent advances in vaccine development, the same technology has been used to produce seasonal influenza vaccines for the past 40 years.
A decrease in immune function is a hallmark of aging and affects the ability to resist influenza virus infection and to respond to vaccination. It is recognized that multiple components of immune function, particularly cell-mediated immunity, are affected during the aging process. As a consequence, there has been a paradigm shift in understanding the limitations of antibody titers as a sole measure of the efficacy of influenza vaccine in older people [4]. Adequate antibody titers may not provide sterilizing immunity in this population [5]. Furthermore, statistically significant increases in antibody titers that correlate with protection in response to vaccination may not translate to clinically important improvements in influenza outcomes in older adults [6]. Thus, the goal of vaccination may be to provide clinical protection against illness mediated by both humoral and cellular immune mechanisms. The challenge to new vaccine development is that antibody titers, when used as a predictor of vaccine efficacy, may fail to detect important changes in cellular immunity that enhance vaccine-mediated protection in older people.
Oxford University Press