The focus of public health interventions is to prevent and manage diseases, injuries and other health conditions through surveillance of cases and the promotion of healthy behavior, communities, and (in aspects relevant to human health) environments. Its aim is to prevent health problems from happening or re-occurring by implementing educational programs, developing policies, administering services and conducting research.[52] In many cases, treating a disease or controlling a pathogen can be vital to preventing it in others, such as during an outbreak. Vaccination programs and distribution of condoms to prevent the spread of communicable diseases are examples of common preventive public health measures, as are educational campaigns to promote vaccination and the use of condoms (including overcoming resistance to such).

Public health has been described as "the science and art of preventing disease, prolonging life and promoting health through the organized efforts and informed choices of society, organizations, public and private, communities and individuals."[51] It is concerned with threats to the overall health of a community based on population health analysis. The population in question can be as small as a handful of people or as large as all the inhabitants of several continents (for instance, in the case of a pandemic). Public health has many sub-fields, but typically includes the interdisciplinary categories of epidemiology, biostatistics and health services. Environmental health, community health, behavioral health, and occupational health are also important areas of public health.
The surviving infant remains healthy and will be closely monitored by Zoo personnel. — Katherine J. Wu, Smithsonian, "National Zoo Reports Death of Infant Golden Lion Tamarin," 2 July 2018 That often pushes aside the basic building blocks of a healthy life, such as proper sleep, exercise, and nutrition. — Clay Marsh, STAT, "Facing deaths of despair from the depths of despair in West Virginia," 12 July 2018 Findings of the study showed 8.2 million years of healthy life were lost due to diabetes attributable to air pollution in 2016 globally. — Hannah Holzer, sacbee, "Air pollution increases risk for type 2 diabetes, study finds," 12 July 2018 Children learned about biker safety and living healthier lives. — Dennis Hohenberger, Courant Community, "Children Learn Bike Safety," 3 July 2018 Our mission has always been to help people live healthier lives. — Carolyn Kylstra, SELF, "How Should a Health Brand Talk About Weight?," 25 June 2018 This process should bring us a step closer to what really matters: informing people who want to know how to eat for a healthy life. — Julia Belluz, Vox, "This Mediterranean diet study was hugely impactful. The science just fell apart.," 20 June 2018 Many say that being involved in different activities has made them happier and healthier. — City Bureau, Chicago Reader, "These candid photos capture how seniors are growing communities—while growing older—on the south side," 12 July 2018 All the activities are monitored by Nicklaus pediatric endocrinology nurses to ensure a safe and healthy environment, according to a news release. — Emily Himes, miamiherald, "Diabetic children learn about nutrition and keeping healthy at Camp Roaring Sun," 10 July 2018

Personal health also depends partially on the social structure of a person's life. The maintenance of strong social relationships, volunteering, and other social activities have been linked to positive mental health and also increased longevity. One American study among seniors over age 70, found that frequent volunteering was associated with reduced risk of dying compared with older persons who did not volunteer, regardless of physical health status.[57] Another study from Singapore reported that volunteering retirees had significantly better cognitive performance scores, fewer depressive symptoms, and better mental well-being and life satisfaction than non-volunteering retirees.[58]
Jump up ^ World Health Organization.Constitution of the World Health Organization as adopted by the International Health Conference, New York, 19–22 June 1946; signed on 22 July 1946 by the representatives of 61 States (Official Records of the World Health Organization, no. 2, p. 100) and entered into force on 7 April 1948. In Grad, Frank P. (2002). "The Preamble of the Constitution of the World Health Organization". Bulletin of the World Health Organization. 80 (12): 982.
The meaning of health has evolved over time. In keeping with the biomedical perspective, early definitions of health focused on the theme of the body's ability to function; health was seen as a state of normal function that could be disrupted from time to time by disease. An example of such a definition of health is: "a state characterized by anatomic, physiologic, and psychological integrity; ability to perform personally valued family, work, and community roles; ability to deal with physical, biological, psychological, and social stress".[7] Then in 1948, in a radical departure from previous definitions, the World Health Organization (WHO) proposed a definition that aimed higher: linking health to well-being, in terms of "physical, mental, and social well-being, and not merely the absence of disease and infirmity".[8] Although this definition was welcomed by some as being innovative, it was also criticized as being vague, excessively broad and was not construed as measurable. For a long time, it was set aside as an impractical ideal and most discussions of health returned to the practicality of the biomedical model.[9]