With better healthcare available and improved accessibility, people are living longer. However, a majority of older persons cannot be considered to be aging well. Approximately 70% of those aged 85 years or older require frequent long hospitalizations because of their increased susceptibility to infections, cancers, dementia, and other age-related health problems, along with overall loss of function and autonomy associated with old age. Previous studies have shown that vaccination against influenza, which significantly reduces all-cause mortality in the elderly (65 years and older), was less immunogenic and effective with age. Frailty, a geriatric syndrome associated with low functional activity, weight loss, exhaustion, disability, decreased resilience to stressors, has been shown to increase risk for adverse outcomes and death. Better understanding the relationship between aging and waning immune responsiveness will enable the development of strategies to improve response to vaccination in the elderly and reduce morbidity and eventually mortality associated with age related complications and outcomes such as infectious diseases or frailty. A comprehensive analysis of the immune phenotype and function after antigenic challenge in older individuals would be a unique approach to understand (i) the potential associations between aging, impaired immune function and transition to frailty, (ii) which components of the immune system are altered with aging (innate vs adaptive immunity) and (iii) if early and/or late immune responses are preferentially altered with aging and frailty.