Report of the ad-hoc consultation on aging and immunization for a future WHO research agenda on life-course immunization.

WHO convened a meeting of around 30 experts to address the topic of aging and immunization in March 2011 in Geneva. The purpose of the meeting was to develop a global research agenda to eventually inform WHO policy recommendations regarding immunization beyond childhood and into old age. This issue is becoming more critical, since the population aged 60 and above will reach two billion people - three-quarters of whom will be in developing countries - in the next 40 years. The meeting reviewed current knowledge and gaps in information about: (1) the epidemiology of infectious diseases in the elderly in developed and developing countries and their contribution to disability in old age; (2) the deterioration of the immune system with age ("immune senescence") and possible ways to measure and counteract it; and (3) immunization approaches to maintain or improve health in older persons. These approaches include the concept of a "life-course vaccination" schedule to help sustain immunity to vaccine-preventable diseases beyond childhood and into old age; strategies to strengthen older persons' responses to vaccines (e.g., by adding adjuvants to vaccines, increasing vaccine dosage, and intradermal vaccine administration); and the possible development of new vaccines targeted specifically for older adults. Participants proposed priority research topics as well as strategies to facilitate and coordinate the research, including the establishment of networks of collaborators, with WHO playing a key coordinating role.