Mednotes

L1 Public Health Introduction to Public Health

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tagspublichealth, lecture, epidemiology, healthdeterminants
aliasesIntroduction to Public Health

22 min read

Overview

The lecture sets out what public health is and how it differs from clinical health care. It moves through three linked parts, as flagged in the lecture outline: definitions of public health (and of the specialty of public health medicine, its core values and its constituent disciplines); frameworks for defining health and its determinants (WHO, Te Whare Tapa Whā, Fonofale, Dahlgren and Whitehead, Barton and Grant) plus frameworks for intervening (Ottawa Charter, Te Tiriti o Waitangi) and the metaphors that capture the field (fence at the top of the cliff, upstream/downstream); and then COVID-19 as a worked example of all of it in action — leadership, epidemiology by person/place/time, prevention, partnership, communication and equity. It closes with the value conflicts public health provokes, the “prevention is a PR disaster” problem, the field’s major achievements and its current challenges (the Sustainable Development Goals), and where public health sits in the ELM curriculum.

Defining public health

Three definitions are given, each cited.

  • Acheson (1988): “public health is the science and art of preventing disease, prolonging life and promoting health through organized efforts of society.”
  • Beaglehole et al. (Lancet, 2004): “Collective action for sustained population-wide health improvement… and the reduction of health inequalities.”
  • John Last, Dictionary of Public Health (2006): “The mission of Public Health is to protect, preserve and promote the health of the public. Public health is the art and science of promoting and protecting good health, preventing disease, disability, and premature death, restoring health when it is impaired, and maximizing the quality of life when health cannot be restored. Public health requires collective action by society; collaborative teamwork involving physicians, nurses, engineers, environmental scientists, health educators, social workers, nutritionists, administrators, and other specialized professional and technical workers; and an effective partnership with all levels of government” — to which the lecturer adds “and community..”

Key points recurring across all three:

  • Science and art — public health is both.
  • Population/collective focus, not the individual patient.
  • Full spectrum of aims: protect, preserve, promote; prevent disease, disability and premature death; restore health when impaired; maximise quality of life when health cannot be restored.
  • Collective action and multidisciplinary teamwork, spanning far beyond doctors.
  • Effective partnership with all levels of government (and community).
  • Reduction of health inequalities as an explicit goal.

Public health medicine as a specialty

Per the New Zealand College of Public Health Medicine (NZCPHM), established as an incorporated society in 2008 to represent the medical specialty in New Zealand and responsible for specialist public health training for doctors who have completed their medical degree and for ongoing professional development of its Fellows:

  • Public health medicine is the branch of medicine concerned with assessment of population health and healthcare needs, development of policy and strategy, health promotion, control and prevention of disease, and organisation of health services.
  • It promotes early upstream action on potential sources of harm to the population’s health, and the building of strong and stable foundations for better and more equitable health for all.

The NZCPHM description was transcribed from a small website screenshot; some wording may be imperfect.

Core principles and values

Core public health principles/values (Williams et al., NZMJ, 24 July 2015, 128(1418)), with the underlying concept the slide annotates beside each:

PrincipleUnderlying concept annotated
Focusing on the health of communities rather than individualsPrevention
Influencing health determinantsTe Tiriti o Waitangi
Prioritising improvements in Māori healthEquity and social justice
Reducing health disparitiesTransport, housing, education, finance
Basing practice on the best available evidenceClimate change, new diseases, war…
Building effective partnerships across the health sector and other sectors
Remaining responsive to new and emerging health threats

The annotation bubbles are positioned by proximity only and are not tied by connectors to particular bullets, so the pairing above is not explicit on the slide.

Scope: what public health includes

Named sub-disciplines:

  • Epidemiology
  • Hauora Māori
  • Health Policy
  • Health Systems
  • Health Promotion
  • Research Methods

The accompanying word cloud adds further terms in the field: Health, Environmental, Economics, Protection, Nutrition, Social, Justice, Activity, Public, Occupational, Global, Physical, Safety.

Take-home point, highlighted on the slide: much of public health exists outside the health sector.

Frameworks and metaphors

Frameworks are used for three distinct purposes:

  1. Defining and understanding ‘health’
  2. Understanding a particular health issue
  3. Designing interventions to improve health

Models of health

WHO definition of health (1946): “a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity.”

Te Whare Tapa Whā (Sir Mason Durie) — hauora (well-being) as a wharenui (meeting house) whose four walls are four dimensions:

  • Taha wairua — spiritual well-being
  • Taha hinengaro — mental and emotional well-being
  • Taha tinana — physical well-being
  • Taha whānau — family and social well-being
  • Foundation of the house: Whenua (land, roots)

Fonofale (Fuimaono Karl Pulotu-Endemann) — a Samoan fale:

  • Roof: Culture
  • Floor/foundation: Family
  • Supporting posts: Physical, Spiritual, Mental, Other
  • Encircling the fale: Environment, Time, Context

Determinants of health

Dahlgren and Whitehead rainbow model — concentric layers around the individual, innermost to outermost:

  1. Age, sex and hereditary factors (fixed, at the centre)
  2. Individual lifestyle factors
  3. Social and community influences
  4. Living and working conditions
  5. General socioeconomic, cultural and environmental conditions

Barton and Grant health map (2006, A health map for the local human habitat, J R Soc Promot Health 126(6)) — an extension of the Dahlgren–Whitehead rainbow, captioned “The determinants of health and well-being in our neighbourhoods”. Layers from the centre outwards, with the examples annotated on each:

  1. PEOPLE — age, sex, hereditary factors
  2. LIFESTYLE
  3. COMMUNITY — social capital, networks
  4. LOCAL ECONOMY — wealth creation, markets
  5. ACTIVITIES — working, shopping, moving, living, playing, learning
  6. BUILT ENVIRONMENT — buildings, places, streets, routes
  7. NATURAL ENVIRONMENT — natural habitats, air, water, land
  8. GLOBAL ECOSYSTEM — climate change, biodiversity

Two-headed arrows at the base link the map to “macro-economy, politics, global forces” and to “other neighbourhoods, other regions” — i.e. the neighbourhood interacts with wider systems in both directions.

Frameworks for intervening

Ottawa Charter for Health Promotion 1986 — intervene at multiple levels:

  • Build healthy public policy
  • Create supportive environments
  • Strengthen community action
  • Develop personal skills
  • Reorient health services
  • (Monitor and evaluate) — greyed out on the slide, i.e. an added/implied sixth item rather than part of the original charter

The charter diagram arranges these five action areas around a central circle holding the three basic strategies: Enable, Mediate, Advocate.

Te Tiriti o Waitangi 1840 — New Zealand’s founding document, presented as a framework for public health. The slide pairs a photograph of the original Treaty sheet with a news photograph of a wooden display panel showing an English version of the Treaty that had been damaged with spray paint and an angle grinder.

Metaphors for public health vs health care

  • Fence at the top of the cliff vs ambulance at the bottom of the cliff: the fence and “CAUTION Cliff edge” sign are public health; the ambulance is health care. Public health prevents harm before it occurs; health care responds after harm has occurred.
  • Upstream vs downstream: on an alpine stream, public health acts upstream on the causes; health care acts downstream on the consequences.

COVID-19: public health in action

The components of the response, as listed:

  • Public health leadership — local, national and international
  • Epidemiology — monitoring; identifying causes and consequences
  • Prevention — vaccination; contact tracing and isolation
  • Community partnerships
  • Communication
  • Strong focus on health equity

Leadership

Seven press photographs of public health leaders are shown. Named on the slide: Dr Tedros Adhanom Ghebreyesus, WHO Director-General; and NSW chief health officer Dr Kerry Chant (captioned with the state reporting a record 356 local Covid cases and three deaths).

The remaining five leaders are not named anywhere on the slide.

Epidemiological monitoring and case definitions

Te Whatu Ora COVID-19 current cases page, 10 February 2025, used as the monitoring example.

Number of active cases (change in the last week | total since first NZ case):

  • Confirmed: 642 | 2,671,391
  • Probable: 2 | 46,538
  • Total: 644* | 2,717,929
  • *The change in total case numbers may not equal the number of new cases reported today, due to data updating and reconciliation.

Total since first New Zealand case: cases reported 2,717,929; reinfections 416,074; reinfections (<90 days) 27,105.

Definitions (circled for emphasis on the slide):

  • Active case – confirmed: a person who has received a positive PCR test, or a positive result on a Rapid Antigen Test.
  • Active case – probable: diagnosed on the basis of exposure to other people with COVID-19 and on symptoms.
  • Reinfection: a case in an individual who reported a case 29 or more days previously.
  • Recovered: had the virus, at least 7 days have passed since symptom onset, no symptoms for 72 hours, and cleared by the health professional responsible for their monitoring.
  • Deceased: all deaths where COVID-19 is determined to have been the underlying cause or a contributory cause of death.

Case definitions determine what the numbers mean; the same surveillance page defines confirmed vs probable, reinfection, recovered and deceased explicitly.

Descriptive epidemiology: person, place, time

The epidemiological triad used to describe an outbreak is person, place, time, each illustrated with COVID-19 data.

Time — epidemic curve of daily confirmed and probable cases (number of cases on the y-axis, 0 to just over 20,000; dates approximately Apr 2020 to Apr 2025): a single very large peak approaching 25,000 daily cases around early-to-mid 2022, followed by successive smaller waves declining over 2023–2024 to near zero by 2025.

The x-axis date labels overlap; individual peak dates cannot be read precisely.

Place — total cases by location (bar chart split by deceased/recovered/active), with the active figure labelled per district: Auckland 534; Bay of Plenty 350; Canterbury 1368; Capital and Coast 529; Counties Manukau 596; Hawke’s Bay 297; Hutt Valley 276; Lakes 193; MidCentral 403; Nelson Marlborough 326; Northland 243; South Canterbury 95; Southern 772; Tairāwhiti 29; Taranaki 235; Unknown 26; Waikato 730; Wairarapa 119; Waitematā 744; West Coast 78; Whanganui 175; At the Border (unlabelled). Total bar length (largely recovered) is greatest for Canterbury, Waitematā, Counties Manukau and Auckland. Alongside it, the contact tracing locations of interest map pins locations across New Zealand, with the caveat that not all locations can be mapped — for example bus routes — and the full list should be consulted.

Person — demographics of cases. Data source note: all data relates to cases recorded prior to 11:59 pm 20 February 2022, collected from the EpiSurv database (administered by ESR) unless otherwise stated.

Cases by age band (% of cases): 0–9 = 14.3%; 10–19 = 17.9%; 20–29 = 23.0%; 30–39 = 18.1%; 40–49 = 11.5%; 50–59 = 8.8%; 60–69 = 4.3%; 70–79 = 1.6%; 80–89 = 0.5%; 90+ = 0.1%.

Cases by ethnicity (emphasised on the slide): Māori 7563, 22.7%; Pacific peoples 10,698, 32[%]; Asian 5715, 17.2%; MELAA 879, 2.6%; European/other 8127, 24.4%; Unknown 335, 1.0%.

The Pacific peoples percentage is cut off on the slide and reads only "10698, 32".

Total cases by sex (active [confirmed and probable] | recovered | deceased | total | % of all cases): Female 8188 | 8384 | 23 | 16,595 | 50%; Male 8146 | 8476 | 30 | 16,652 | 50%; Unknown 37 | 33 | 0 | 70 | 0%; Total 16,371 | 16,893 | 53 | 33,317 | 100%.

Epidemiology translated into action

Two news examples of epidemiological data driving policy:

  • **40m to Māori and Pacific health providers, 40m to build on the Māori Communities Covid-19 Fund, and $1.75m for the Karawhiua Māori vaccination campaign.
  • Prioritisation of COVID-19 vaccine for Māori and Pacific now a matter of urgency (nzdoctor.co.nz, Undoctored, 24 August 2021): as Delta cases continued to increase, prioritising Māori and Pacific for vaccination was necessary and urgent — Dr Collin Tukuitonga, Pasifika Medical Association.

Clash of values

Public health action provokes value conflicts. Two worked examples are given.

COVID-19 mandates

Set over a photograph of an anti-mandate protest with placards reading “WHEN INJUSTICE BECOMES LAW RESISTANCE BECOMES A DUTY” and “Say NO TO MEDICAL APARTHEID — FREEDOM NOT Facism!” [sic].

Public healthVs…. (opposing position, unheaded on the slide)
Utility (greatest good for greatest number)Autonomy (individual freedom)
Health and health equity (protection of most vulnerable)Personal responsibility
Prioritise Hauora Māori”died with covid not of covid..”
Focus on communities rather than individualsMistrust of authority figures and scientific evidence
Decisions evidence basedGovernment should have minimal role in people’s lives
Government has essential role

Illustrated by a photograph of social drinking and an RNZ article headlined “Medical experts appeal for select committee scrutiny of smokefree law changes”.

Public healthVs….
Focus on healthy environmentsIndividual freedom
Health and health equity (protection of most vulnerable)Personal responsibility
Focus on communities rather than individualsGovernment should have minimal role in people’s lives
Decisions evidence basedIndustry should regulate itself
Government has essential role in regulating sale and supply of harmful commodities”Legal product…”
Government intervention = “Nanny State”

Prevention: a PR disaster

Made via a parody Winnie-the-Pooh caption:

“But how will we know if our pandemic guidelines work?” asked Piglet. “The world will think we overreacted,” said Pooh. “So even when we’re right, everyone thinks we’re wrong?” “Welcome to Public Health,” said Pooh. And Piglet understood.

Successful prevention is invisible, so effective public health action is perceived as an overreaction — hence "prevention is a PR disaster".

Public health achievements

Two national “top 10” lists.

Australia (PHAA, Top 10 public health successes over the last 20 years, PHAA Monograph Series No. 2, Canberra, 2018):

  1. Folate: reduced neural tube defects
  2. Immunisation and eliminating disease
  3. Elimination of cervical cancer
  4. Oral health: reduced dental decay
  5. Reduced incidence of skin cancer in young adults
  6. Fewer people dying due to smoking
  7. Brought down the road death and injury toll
  8. Gun control: reduced gun deaths
  9. HIV: contained the spread
  10. Finding cancer early: prevented deaths from bowel and breast cancer

USA (Ten Great Public Health Achievements — United States, 2001–2010, MMWR Vol. 60 No. 19, 2011):

  1. Reduction in vaccine-preventable diseases
  2. Prevention and control of infectious diseases
  3. Tobacco control
  4. Maternal and infant health
  5. Motor vehicle safety
  6. Cardiovascular disease prevention
  7. Occupational safety
  8. Cancer prevention
  9. Childhood lead poisoning prevention
  10. Public health preparedness and response

Public health challenges

Presented as the 17 UN Sustainable Development Goals:

  1. No Poverty; 2. Zero Hunger; 3. Good Health and Well-being; 4. Quality Education; 5. Gender Equality; 6. Clean Water and Sanitation; 7. Affordable and Clean Energy; 8. Decent Work and Economic Growth; 9. Industry, Innovation and Infrastructure; 10. Reduced Inequalities; 11. Sustainable Cities and Communities; 12. Responsible Consumption and Production; 13. Climate Action; 14. Life Below Water; 15. Life on Land; 16. Peace, Justice and Strong Institutions; 17. Partnerships for the Goals.

Public health in the ELM curriculum

  • A series of lectures (and one tutorial) through ELM2 and ELM3, aligned with block modules.
  • More exposure to public health in ALM (block module).
  • Contact: Professor Rachael McLean, rachael.mclean@otago.ac.nz

ELM2 public health teaching schedule:

DateTopic
18 FebIntroduction to Public Health
26 FebRoad traffic injury prevention
1 MayControl of infectious disease
15 JulWhat can we do to prevent disease?
17 JulHeart health for New Zealanders
31 JulEpidemiology of asthma
31 JulSmokefree 2025: what, why and how… and what has it got to do with doctors?
6 AugScreening for lung cancer
9 SepPublic Health: Responding to wicked complex problems
10 SepInterventions: Sugar tax
1 OctHIV — Epidemiology, clinical care and microbiology overview

Self-test

  1. State Acheson’s 1988 definition of public health.
  2. State Beaglehole et al.’s 2004 definition of public health.
  3. List the elements of the mission of public health as given by John Last, and name the addition the lecturer makes to it.
  4. Define public health medicine as the NZCPHM describes it.
  5. List the seven core public health principles/values from Williams et al. (2015).
  6. List the six sub-disciplines named as part of public health, and state the highlighted take-home point about where public health sits.
  7. List the three purposes for which public health frameworks are used.
  8. State the WHO 1946 definition of health, and explain what it adds beyond the absence of disease.
  9. Name the four dimensions of Te Whare Tapa Whā and the foundation of the house.
  10. Describe the components of the Fonofale model, including roof, floor, posts and surrounding elements.
  11. List the five layers of the Dahlgren and Whitehead model from the centre outwards.
  12. List the eight layers of the Barton and Grant health map from the centre outwards, with one example annotated on each.
  13. Explain how the Barton and Grant map differs from the Dahlgren and Whitehead rainbow.
  14. List the five action areas of the Ottawa Charter and the three basic strategies at its centre.
  15. Explain why “(Monitor and evaluate)” is shown differently from the other Ottawa Charter items.
  16. Explain the “fence at the top of the cliff vs ambulance at the bottom” metaphor and what each element represents.
  17. Distinguish “upstream” from “downstream” action using the stream metaphor.
  18. List the six components of the COVID-19 public health response given in the lecture.
  19. Distinguish a confirmed active case of COVID-19 from a probable active case.
  20. State the Te Whatu Ora definitions of reinfection, recovered and deceased for COVID-19.
  21. Name the three dimensions of descriptive epidemiology and state which COVID-19 figure was used to illustrate each.
  22. Describe the shape of the New Zealand COVID-19 epidemic curve from 2020 to 2025.
  23. State the three age bands with the highest percentage of COVID-19 cases, with their percentages.
  24. Describe what the cases-by-ethnicity data showed, and note the limitation in reading it from the slide.
  25. Explain how the COVID-19 epidemiological data was translated into government action, giving one funded example.
  26. List four public health values and the four opposing values set against them in the COVID-19 mandate “clash of values”.
  27. Distinguish the public health position from the opposing position on regulating alcohol and tobacco.
  28. Explain why prevention is described as “a PR disaster”.
  29. List five of the Australian top 10 public health successes.
  30. List five of the USA’s ten great public health achievements 2001–2010.
  31. State how public health challenges were framed in this lecture.
  32. A district reports a rising number of cases concentrated in one age band and one ethnic group. Using the person/place/time framework and the lecture’s COVID-19 example, describe how you would characterise the outbreak and what kind of action the data should trigger.
  33. A government proposes restricting the sale and supply of a legal but harmful commodity. Predict the arguments that will be made against it, and give the public health counter-position for each.
  34. Integrative: using the Dahlgren and Whitehead determinants, the Ottawa Charter and the upstream/downstream metaphor, explain why public health focuses on communities rather than individuals and why much of public health exists outside the health sector.

Answers

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