Whilst the vast majority of health expenditure is currently dedicated to treatment and therapeutics, about 70% of health gains from known interventions could be achieved through prevention: such as encouraging healthier behaviours, creating healthier environments or vaccination. To better understand the potential of prevention, it is possible to categorise prevention into three levels: primary, secondary and tertiary:

Primary Prevention

Primary prevention aims to prevent disease and injury from occurring. The aim of primary prevention would thus be to identify, reduce and eliminate risk factors. Examples of primary prevention include vaccination, encouraging healthy habits or altering harmful behaviours, such as tobacco use.

Secondary Prevention

Secondary prevention seeks to intervene as soon as possible at the onset of disease through early diagnosis and timely treatment. Its goal is to maximise the effectiveness of treatment at the early stages of disease, enhancing the curative effects while minimising the chances of progression.

Mammography, cervical cancer screening and regular blood pressure testing are examples of secondary prevention of breast cancer, cervical cancer and hypertension respectively.

Tertiary Prevention

Tertiary prevention involves managing diseases post diagnosis and aims to prevent sequelae or more severe consequences of existing disease, or to improve quality of life, physical and mental functioning and life expectancy. Tertiary prevention can be enacted through, for example, screening for complications, rehabilitation, or chemotherapy.