Immunosenescence: Implications for vaccination programmes in adults.

Vaccination is crucially important in preventing infection and protecting vulnerable population from infectious diseases. However, a multitude of changes in the immune system occurring with advancing age, termed immunosenescence, lead to limit the protective effects of vaccination in older adults. While it is widely believed that the current immunization strategies saves many lives, vaccine preventable infectious diseases (VPDs) still place a considerable burden, not only on older individuals, but also on the adult population and healthcare systems of developed countries. This review will first examine the evidence linking the contribution of immunosenescence to a less than optimal vaccine response in aged individuals in order to demonstrate that strategy of promoting vaccination in these populations is not sufficient to reduce the burden associated with VPDs. Furthermore, based upon the side effects of the herd immunity when vaccine-policies are mainly childhood-centered, considerations will be given on the imperative necessity to frame shift our thinking and efforts away from a nearly complete childhood-centered vaccine programme toward a life-span immunization programmes.