In the 19th century public health operated at a local level with a focus on disease control. This was addressed through quarantine measures, sanitary reform and vaccination.
Quarantine – an enforced period of isolation – was the first line of defence against infectious diseases in the 19th century. All people on board ships affected by disease were quarantined on islands. This occurred less frequently later in the century as large, spacious steamships replaced sailing ships, and screening before departure improved. However, quarantining did not officially cease until 1943. During the COVID-19 coronavirus pandemic in 2020–21, people arriving in the country from overseas were required to isolate for 14 days after arrival, either at home or in hotels set aside for this purpose.
The Public Health Act 1872 set up a central board of health for each province and smaller local boards (which were usually the borough and city councils) within each province. After the provinces were abolished in 1876, one country-wide board controlled by central government was established, while local boards were retained. Both levels were poorly funded and neither very active nor effective.
The Christchurch Drainage Board (1876–85) was one exception. It employed a full-time medical officer and was responsible for significant sanitation improvements, including the first sewerage system in New Zealand (completed in 1882). This led to a reduction in deaths from infectious diseases such as typhoid.
From the 1880s doctors advocated a central department of health, which the government was also considering. The (ultimately unrealised) threat of a bubonic plague pandemic reaching New Zealand provided the impetus needed to establish the Department of Public Health in 1900.
The department (from 1922 called the Department of Health, and from 1992 the Ministry of Health) was responsible for the identification of public health issues and the development of preventative and promotional public health services, which were delivered by regional offices. The role of the Ministry of Health in overseeing public health was enshrined in the Health Act 1956.
In the 1990s the government concentrated on financial efficiency and health services for individuals. Resources were directed away from public health. An independent Public Health Commission was established in 1993 to conduct research, develop policy and contract out public health programmes, but it was disbanded in 1996.
In the 2000s the government made public health a priority. District health boards were required to promote and improve the health of communities under the New Zealand Public Health and Disability Act 2000. The Ministry of Health planned and managed public health services – immunisation, tobacco control and mental health promotion – on a national level, while regional district health board public health units or non-governmental organisations delivered them. A Public Health Advisory Committee was established in 2001 (as a sub-committee of the National Health Committee) to provide independent advice to the minister of health.
Some aspects of public health previously administered by the ministry became overseen by separate government agencies. The New Zealand Food Safety Authority was responsible for food safety and the Department of Labour for occupational health. Other government agencies (for example, those with social welfare, housing and transport responsibilities) also played a role in public health.
The Health Act 1956 gave local government powers to employ environmental health officers, enact bylaws, and to identify and address 'nuisances' that could be injurious to health.
The Local Government Act 2002 conferred on local government a new, broader statutory responsibility for ‘promoting the social, economic, environmental, and cultural well-being of their communities’. Water, waste and sanitation services have remained key local-government public health responsibilities. Other functions that have had an impact on public health include the provision of recreational facilities and public transport.
The Health Act 1956 describes things that are offensive or potentially injurious to public health as ‘nuisances’. There are 17 separate nuisances. They are created, for example, ‘where any animal, or any carcass or part of a carcass, is so kept or allowed to remain as to be offensive or likely to be injurious to health’ or ‘where there exists on any land or premises any condition giving rise or capable of giving rise to the breeding of flies or mosquitoes or suitable for the breeding of other insects, or of mites or ticks, which are capable of causing or transmitting disease’.
Numerous other health and non-health agencies are involved with delivering public health functions.
The Health Promotion Agency leads and supports initiatives to promote health and well-being, encourage healthy lifestyles and environments, and prevent disease, illness and injury.
Plunket (originally the Society for the Promotion of the Health of Women and Children), which from 1907 provided public health services for infants and children under five, was the earliest non-government public health organisation.
Many other non-government organisations (NGOs) are involved with public health interventions and advocacy. For example, Hāpai Te Hauora delivers regional Māori public health services as well as holding national service contracts for gambling harm minimisation, tobacco control advocacy and sudden unexpected death in infancy (SUDI) prevention. Other leading NGOs include the Cancer Society of New Zealand, the Public Health Association of New Zealand, and professional bodies such as the New Zealand College of Public Health Medicine.
By the 2000s about 50% of the public health section of the overall health budget was allocated to non-governmental organisations to deliver services to the community.
In the 21st century general practitioners and other health professionals who grouped together as primary health organisations (PHOs) were given the mandate to improve and maintain the health of the population through the delivery of national public health services such as immunisation. PHOs also had a limited role in health promotion.
Tertiary-education institutions provided postgraduate training in public health, while university-based research was an essential source of information for the public health sector. The Public Health Association, a voluntary organisation, promoted public health and assisted in policy development.