Problems and solutions to the development of vaccines in the elderly

One of the major target populations for vaccination is the ever-increasing cohort of persons aged 65 and older, a group that is characterized by high morbidity and mortality from infections that partly are caused by reduced immune function. Many elderly persons also show suboptimal response to vaccines that are intended to prevent infection. A new immune biomarker of reduced antibody response to vaccination is the presence of a high proportion of memory CD8 T cells that lack expression of the CD28 costimulatory molecule. This article discusses some of the challenges involved in custom-designing vaccines that account for the remodeled immune system of the elderly.