social and economic impacts of influenza (flu)

Cambridge AS & A‑Level Geography (9696) – Disease & Geography
Case Study: Social and Economic Impacts of Influenza (Flu)

1. Syllabus Mapping (What the examiner expects)

2. Physical Basis of Influenza Transmission

2.1 Atmospheric Drivers

• Temperature: Virus envelope proteins are stable between 5‑15 °C; above 25 °C they denature rapidly.
• Absolute Humidity (AH): Measured in g m⁻³; AH < 5 g m⁻³ favours aerosol transmission. Relative humidity (RH) is less reliable because it varies with temperature.
• Precipitation & Cloud Cover: Heavy rain reduces outdoor exposure but increases indoor crowding; cloud cover reduces UV‑induced viral decay.
• Large‑Scale Circulation: In temperate zones, the subtropical high and mid‑latitude westerlies shift the jet stream southward in winter, bringing dry, cool air masses that lower AH across large regions.

2.2 Climate‑Change Interaction

2.3 Epidemiological Modelling (AO2)

A simple SIR (Susceptible‑Infectious‑Recovered) model illustrates the dynamics of seasonal flu:

• β (transmission coefficient): Increases when AH falls and indoor contact rises.
• γ (recovery rate): Approximately 1/5 days⁻¹ for typical flu.
• R₀ = β/γ: 1.2‑1.8 for seasonal strains; > 2 for pandemic strains (e.g., H1N1 2009).

Diagram placeholder: SIR flow diagram with arrows showing S → I → R and feedback from environmental drivers to β.

3. Social Impacts – How Influenza Affects People and Communities

3.1 Health Burden

• Incidence: 5‑10 % of temperate‑zone populations per season; up to 20 % in tropical zones with year‑round transmission.
• Mortality: Concentrated in the very young, elderly and immunocompromised; case‑fatality rate ≈ 0.1 % for seasonal flu, ≈ 0.02 % for pandemic H1N1.
• Health‑service pressure: Emergency department attendances rise 15‑25 % during peak weeks; elective surgeries postponed by up to 12 %.

3.2 Education

• Average school closures: 5‑10 days per season in high‑income countries; up to 3 weeks in low‑income settings where outbreak control is less effective.
• Absenteeism: 8‑12 % of pupils absent on peak days; widening attainment gaps, especially for pupils from low‑income families who lack access to remote learning.
• Mitigation: Hand‑sanitiser stations and staggered timetables can cut absenteeism by 20‑30 % (evidence from a 2019 UK pilot).

3.3 Population & Migration

• Demographic pyramids: Ageing societies (e.g., Japan, Italy) have higher vulnerability because the proportion of > 65 year‑olds exceeds 20 %.
• Internal displacement: Seasonal workers from dense urban districts temporarily return to rural homes, reducing urban transmission but raising risk in peri‑urban clinics.
• Cross‑border travel: During severe seasons, international tourism drops 5‑15 % (UNWTO data 2017‑18); airline seat occupancy falls 2‑4 %.
• Place‑based examples:
  • High‑income: United Kingdom – rapid urban spread in London.
  • Middle‑income: Vietnam – dense megacities (Ho Chi Minh) see earlier peaks due to monsoon‑driven humidity swings.
  • Low‑income: Kenya – limited cold‑season but year‑round transmission linked to livestock‑associated avian influenza.

3.4 Water Resources & Sanitation

• Peak‑week water demand for hand‑washing rises 15‑20 % in urban utilities (e.g., Thames Water, 2018).
• Per‑capita water‑use intensity during flu peaks: 120 L person⁻¹ day⁻¹ (vs. 100 L person⁻¹ day⁻¹ baseline) in high‑income cities; up to 30 % higher in informal settlements where water is scarce.
• Wastewater load increases 10‑12 % due to higher flushing of disinfectants and medicines, stressing treatment plants.

3.5 Mobility & Transport

• Public‑transport ridership falls 8‑12 % during peak weeks (London Underground, 2017‑18).
• Freight volumes remain stable; essential goods supply chains are resilient.
• Event cancellations: average 3‑5 % of scheduled cultural events postponed in major cities each flu season.

3.6 Stigma, Mental Health & Equality

• Fear of infection can lead to social isolation, anxiety, and discrimination (e.g., stigma against migrant workers in Singapore during H1N1).
• Vaccine hesitancy is higher among some ethnic minorities (e.g., 22 % non‑vaccination rate among Black African groups in the UK, 2018).
• Low‑income households face higher exposure (crowded housing) and lower access to vaccination (cost, transport barriers).

4. Economic Impacts – Quantifying the Cost of Influenza

4.1 Direct Costs

• Medical consultations, hospital admissions, antivirals, vaccines.
• UK (2017‑18) NHS expenditure: £400 million (≈ £2 per capita).
• US (2009 H1N1) direct health‑care cost: US$15‑20 billion.

4.2 Indirect Costs

• Lost workdays, reduced output, overtime for essential services.
• Productivity‑loss formula (AO2):
  Productivity Loss = Σ (Workers absent × Average weekly wage)
• UK (2017‑18) estimate: £800 million (≈ 0.03 % of GDP).
• Vietnam (2018) estimated loss: US$1.1 billion (≈ 0.15 % of national GDP).

4.3 Sector‑Specific Effects

4.4 Macroeconomic Consequences

• Seasonal flu can cause a temporary GDP contraction of 0.1‑0.5 % in severe years (e.g., US 2009 H1N1 ≈ 0.3 %).
• Fiscal pressure: increased public‑health spending competes with education and infrastructure budgets.

5. Global Health Governance & Management (AO3)

5.1 International Frameworks

• World Health Organization (WHO) International Health Regulations (2005) obligate member states to report influenza outbreaks, share virus samples, and coordinate vaccine strain selection.
• Global Influenza Surveillance and Response System (GISRS) – 142 national influenza centres provide weekly virological data used for vaccine composition.

5.2 National Mitigation Strategies

1. Vaccination programmes – Annual WHO‑recommended campaigns targeting > 75 % coverage in high‑risk groups. Cost‑benefit analysis (UK 2020) shows a return of £2.5‑£4 for every £1 invested (NHS Economic Evaluation).
2. Public‑health communication – Clear, culturally‑sensitive messaging reduces stigma and improves early‑treatment uptake (e.g., SMS alerts in Kenya reduced delay to care by 30 %).
3. Flexible work & remote‑working – Employers report a £150 million productivity saving in the UK (2017‑18) by allowing home‑based sick days.
4. School hygiene policies – Installation of hand‑sanitiser stations and staggered break times cut absenteeism by up to 30 % (pilot in Manchester, 2019).
5. Water‑resource prioritisation – Designating “hand‑washing zones” in high‑density districts ensures adequate supply during peaks.
6. Surveillance & rapid response – GISRS data feed into national pandemic‑influenza preparedness plans; real‑time dashboards enable targeted school closures.

5.3 Evaluation – Benefits, Limitations & Uncertainties

6. Case Study Snapshots (Place – Low, Middle & High Income)

6.1 United Kingdom – 2017/18 Seasonal Flu (High‑income)

• GP consultations for ILI: ≈ 2.5 million.
• Total economic cost: £1.2 billion (Direct £400 m + Indirect £800 m).
• Peak weeks (Weeks 6‑9): 15 % rise in hospital admissions; 8 % drop in rail passenger numbers; water demand ↑ 18 %.

6.2 United States – 2009 H1N1 Pandemic (High‑income)

• Estimated 60 million cases, 12 000 deaths.
• Economic impact: US$45‑55 billion (≈ 0.3 % of US GDP).
• School closures affected > 30 % of districts; airline passenger numbers fell 10 % during the peak month.

6.3 Vietnam – Seasonal Flu in a Tropical‑Monsoon Climate (Middle‑income)

• Two annual peaks linked to the dry (Nov‑Feb) and rainy (May‑Oct) seasons.
• Incidence ≈ 12 % of population per year; higher in Ho Chi Minh City (density > 4 000 km⁻²).
• Direct health‑care cost: US$120 million; indirect loss: US$250 million (mainly agricultural labour).

6.4 Kenya – Avian Influenza (Low‑income)

• 2006‑07 H5N1 outbreak in poultry farms; 30 % of commercial flocks culled.
• Human cases: 22 confirmed, 13 deaths (CFR ≈ 59 %).
• Economic loss: US$75 million from poultry export bans and loss of household income.
• Limited vaccination infrastructure; reliance on community‑based education for hygiene.

7. Suggested Diagram for Exam Answers

Transmission pathways of influenza (flow diagram) – show:

1. Environmental drivers (temperature, AH, precipitation, large‑scale circulation).
2. Animal reservoirs (wild birds, swine) → zoonotic spill‑over.
3. Human‑to‑human spread (droplets, aerosol droplet nuclei, fomite contact).
4. Socio‑economic feedbacks (mobility, health‑service demand, water use, economic loss).
5. Global governance loop (GISRS → vaccine strain selection → national vaccination → reduced transmission).

Use arrows to indicate cause‑effect and feedback loops; colour‑code environmental vs. social components.

8. Integrated Summary Table – Social & Economic Impacts

9. Revision Checklist (Key Take‑aways)

• Seasonality is driven by temperature, absolute humidity, and large‑scale atmospheric circulation; climate change may shift these patterns.
• Social impacts are multi‑layered: health, education, migration, water demand, urban disruption, mental health, and inequality.
• Economic costs split into direct medical expenses and indirect productivity losses; sectoral knock‑on effects can be quantified.
• Effective mitigation (vaccination, communication, flexible work, school hygiene, water‑resource prioritisation) reduces both social disruption and economic burden, but equity and logistical challenges must be addressed.
• When answering exam questions, always link impacts to the required key concepts (scale, change over time, place, spatial variation, cause‑effect, systems, challenges & opportunities, diversity/equality) and reference the relevant AO (AO1‑AO3).