Acute respiratory tract infections (ARTI) are responsible for more disability than any other acute illnesses in the United States. In the under 65 year old population, ARTI in aggregate are the major causes of absenteeism from school and work, decreased activity, and bed disability. Despite the well described episodic impact on mortality attributable to acute respiratory illness in the institutionalized and hospital bound elderly, very little information is available on the potential impact of the more common ARTI on the functional state of the frail elderly who are still being maintained in the community usually by a complex social and health care network. If ARTI have at lease a comparable disabling effect as observed in the younger population, these illnesses may represent some of the most important undefined factors leading to a decline in functional state and loss of independence in the frail elderly. Moreover, compared to other established and more well studied sentinel events leading to functional decline, such as coronary artery disease, hip fracture, acute cerebrovascular ischemia, ARTI may encompass some of the factors most amenable to primary and secondary interventional strategies. We propose therefore to test two major hypotheses concerning the relationship of ARTI to changes in functional state in a community dwelling frail elderly population: 1. The incidence, responsible pathogens, and modes of transmission of ARTI in non-institutionalized frail elderly will have a predictable epidemiologic pattern which will correlate with the over-all community pattern of infection at all age levels. The impact of intergenerational programs, i.e. contiguous adult and child day care centers, will be evaluated. These illnesses will have at least a comparable impact on reduction of independence as observed in the younger population and will be causally linked to clinically significant decline in the functional state of frail elderly, often being the sentinel event leading to deconditioning and eventually institutionalization. In addition to leading to transient worsening of known areas of functional disability, ARTI will be associated with the transient development of new domains of functional dependence. 2. Given an understanding of these predictable community patterns of ARTI in non-institutionalized frail elderly, specific interventions will result in less deconditioning, functional decline, and expenditures for health care. These specific interventions are: 1. Preventive Deconditioning, 2. Infection control to prevent nosocomial infection, 3. Respiratory Viral Vaccines.