IL6 and influenza: It has been shown that age-related changes of the T cell compartment, interpreted as indicators of biological aging of the immune system, are correlated with impaired immune responses to influenza vaccination [19,32,33] and that the antibody response to pneumococcal vaccination is decreased in frail elderly [34], which show increased levels of inflammatory molecules, such as IL-6 and neopterin suggestive of “inflammaging” [26,35,36].