The great positive impact of public health programs is widely acknowledged. Due in part to the policies and actions developed through public health, the 20th century registered a decrease in the mortality rates for infants and children and a continual increase in life expectancy in most parts of the world. For example, it is estimated that life expectancy has increased for Americans by thirty years since 1900, and worldwide by six years since 1990.
Prescription drug plans are a form of insurance offered through some health insurance plans. In the U.S., the patient usually pays a copayment and the prescription drug insurance part or all of the balance for drugs covered in the formulary of the plan. Such plans are routinely part of national health insurance programs. For example, in the province of Quebec, Canada, prescription drug insurance is universally required as part of the public health insurance plan, but may be purchased and administered either through private or group plans, or through the public plan.
Health, as defined by the World Health Organization (WHO), is "a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity." This definition has been subject to controversy, as it may have limited value for implementation. Health may be defined as the ability to adapt and manage physical, mental and social challenges throughout life.