CD8A and influenza: In fact, reverse metabolic syndrome is associated with increased mortality in the older adults, while body mass index (BMI) >30 significantly correlates with protection and improved survival.51,52 Obesity is associated with reduced ability to respond to influenza vaccination53,54 and HBV.55 In contrast, caloric restriction in animals increases thymic cellularity (CD4+ and CD8+) with increased in vitro responses to antigens.56