# HPV Vaccine Impact: Cervical Cancer Prevention Globe Visualization

**Iteration 14** in the Mapbox Globe progressive learning series.

## Overview

An advanced multi-dimensional globe visualization demonstrating the global success and stark inequity of HPV (Human Papillomavirus) vaccination programs in preventing cervical cancer. This visualization combines vaccine coverage data, cancer incidence rates, mortality statistics, and projected lives saved across 146 countries.

## The Story Behind the Data

### HPV Vaccine: A Modern Medical Success Story

- **2006**: First HPV vaccine approved, targeting cancer-causing viral strains
- **Target**: Prevent cervical cancer (4th most common cancer in women globally)
- **2024**: 146 countries have national vaccination programs
- **Impact**: 87% reduction in cervical cancer rates in vaccinated cohorts

### The Global Health Inequity

Despite the vaccine's proven effectiveness:

- **High-income countries**: 84% average coverage
- **Low-income countries**: 27% average coverage
- **Devastating disparity**: 90% of cervical cancer deaths occur in low/middle-income countries
- **Preventable tragedy**: 311,000 lives could be saved annually with universal coverage

## Features

### Multi-Layer Visualization

1. **Circle Layer**: Vaccine coverage and cancer correlation
   - Size encodes one metric (coverage, cancer rate, lives saved, mortality)
   - Color encodes another metric (4×4 = 16 visualization combinations)
   - Special highlighting for countries without vaccination programs

2. **3D Extrusion Layer**: Cancer burden visualization
   - Column height represents annual cervical cancer deaths
   - Color represents cancer incidence rate
   - Toggle between 2D and 3D views
   - Automatic camera pitch adjustment

3. **Labels Layer**: High-burden countries
   - Automatic labeling for countries with >2,000 annual deaths
   - Size proportional to death burden

### Interactive Controls

- **Size Metric Selector**: Choose what circle size represents
  - HPV Vaccine Coverage (%)
  - Cervical Cancer Incidence (per 100,000)
  - Lives That Could Be Saved
  - Cervical Cancer Mortality (per 100,000)

- **Color Metric Selector**: Choose what circle color represents
  - Same four metrics as size, independently selectable

- **3D Cancer Burden Toggle**: Switch between 2D and 3D visualization modes

- **Globe Controls**: Pause/resume rotation, reset view

### Data Dimensions

Each country includes:
- **HPV coverage**: Current vaccination rate (2024)
- **Program start year**: When national program began
- **Target age**: Typical age range for vaccination
- **Cancer incidence**: Cases per 100,000 women
- **Cancer mortality**: Deaths per 100,000 women
- **Income level**: High, upper-middle, lower-middle, or low
- **Lives saved potential**: Deaths preventable with full coverage
- **Gender policy**: Girls-only or girls-and-boys programs
- **Annual deaths**: Current yearly death toll

## Key Insights Revealed

### Coverage Patterns

**Champions (>85% coverage)**:
- Rwanda (93%) - Low-income country, exceptional program
- Bhutan (94%) - Small nation, universal reach
- Australia (92%) - Early adopter, comprehensive program
- Oman (93%) - High-income Gulf state investment

**Laggards in high-income countries**:
- Japan (18%) - Program suspended due to safety concerns, recently restarted
- Poland (19%) - Late adoption, rolling out
- France (46%) - Vaccine hesitancy challenges

### Cancer Burden Patterns

**Highest incidence rates**:
- Eswatini (44 per 100K) - HIV co-infection factor
- Malawi (42.1 per 100K) - Limited screening access
- Tanzania (40.1 per 100K) - Low vaccination coverage
- Uganda (40.1 per 100K) - Recent program start

**Lowest incidence rates**:
- Finland (4.8 per 100K) - High coverage + screening
- Iran (4.3 per 100K) - Cultural factors + program adoption
- Oman (4.2 per 100K) - Strong public health system

### Lives Saved Potential

**Largest potential impact** (with full coverage):
- India: 86,000 lives/year (37% current coverage)
- China: 52,000 lives/year (34% current coverage)
- Nigeria: 26,500 lives/year (12% current coverage)
- Indonesia: 24,500 lives/year (31% current coverage)

### Gender Policy Insights

**Progressive programs** (vaccinating both girls and boys):
- 22 countries have gender-inclusive policies
- Benefits: Herd immunity, oral/throat cancer prevention
- Examples: Canada, UK, Australia, Spain, Austria, Panama

**Traditional programs** (girls-only):
- 124 countries focus on direct cervical cancer prevention
- Rationale: Cost-effectiveness in resource-limited settings

## Technical Implementation

### Advanced Mapbox Techniques

1. **Interpolate Expressions**
   - 4 distinct size scales (coverage, cancer-rate, lives-saved, mortality)
   - 4 distinct color scales with semantic color theory
   - Diverging scales for quality metrics (green=good, red=poor)
   - Sequential scales for magnitude metrics (dark=low, light=high)

2. **Case Expressions**
   - Conditional stroke highlighting for countries without programs
   - Dynamic stroke width based on program presence

3. **Fill-Extrusion Layer**
   - 3D column heights for cancer death burden
   - Color encoding for incidence rates
   - Toggleable visibility with smooth transitions

4. **Zoom-Based Expressions**
   - Adaptive opacity (lower at global scale, higher when zoomed)
   - Dynamic stroke width scaling
   - Label visibility thresholds

### Color Theory & Semantic Design

**Coverage Gradient** (Purple theme):
- Dark purple (0%) → Light purple (95%)
- Purple chosen as "healthcare/awareness" color
- Connects to cervical cancer awareness campaigns

**Cancer/Mortality Gradient** (Green-to-Red diverging):
- Green (low incidence) = good outcome
- Yellow (moderate) = warning
- Red (high incidence) = crisis
- Intuitive health status visualization

**Lives Saved Gradient** (Teal sequential):
- Neutral color (neither positive nor negative connotation)
- Represents potential and opportunity
- Darker = less potential, lighter = more lives at stake

## Gender Equity & Health Justice

This visualization exposes critical global health inequities:

### The Gender Dimension

Cervical cancer is:
- **Almost entirely preventable** through vaccination and screening
- Disproportionately affects women in low-resource settings
- **4th most common cancer** in women globally
- Rare in men but preventable through vaccination (oral/throat cancer)

### The Economic Dimension

**High-income country advantages**:
- Early vaccine access (2006-2010 program starts)
- School-based delivery systems
- High coverage rates (70-95%)
- Strong screening programs for early detection

**Low-income country challenges**:
- Late vaccine access (2015-2023 program starts)
- Limited healthcare infrastructure
- Supply chain difficulties
- Competing health priorities
- Coverage rates often <50%

### The Result

**90% of cervical cancer deaths occur in low/middle-income countries**, despite the vaccine being available for 18 years. This represents a profound failure of global health equity.

## Usage

### Opening the Visualization

1. Open `index.html` in a modern web browser
2. The globe will auto-rotate, showing global coverage patterns
3. Hover over countries to see detailed statistics
4. Use controls to explore different metric combinations

### Recommended Explorations

**Explore the coverage-cancer correlation**:
1. Set Size = "HPV Vaccine Coverage"
2. Set Color = "Cervical Cancer Incidence"
3. Observation: Large purple circles (high coverage) mostly have green color (low cancer)
4. Small dark circles (low coverage) often have red/orange color (high cancer)

**Identify high-impact opportunities**:
1. Set Size = "Lives That Could Be Saved"
2. Set Color = "HPV Vaccine Coverage"
3. Observation: Large dark purple circles = huge potential, low current coverage
4. These are the countries where investment would save the most lives

**Visualize the burden**:
1. Click "Toggle 3D Cancer Burden"
2. Tall columns = high annual deaths
3. Rotate the globe to see regional patterns
4. Sub-Saharan Africa and South Asia show the tallest columns

**Compare income levels**:
1. Set Size = "HPV Vaccine Coverage"
2. Set Color = "Cervical Cancer Incidence"
3. Zoom to different regions
4. North America/Europe: Large purple circles, green color
5. Africa/South Asia: Smaller circles, red/orange color

## Data Sources

- **HPV Coverage**: WHO, GAVI Alliance, National Health Ministries (2024 data)
- **Cancer Incidence**: Global Cancer Observatory (GLOBOCAN 2022)
- **Mortality Rates**: WHO International Agency for Research on Cancer (IARC)
- **Program Details**: HPV Information Centre, National Vaccination Schedules
- **Lives Saved Projections**: WHO cervical cancer elimination strategy models

### Data Notes

- Coverage rates represent the percentage of the target population (typically girls aged 9-14) who have completed the vaccination series
- Incidence rates are age-standardized per 100,000 women
- Lives saved projections assume 90% coverage and account for the 10-15 year lag between vaccination and cancer prevention
- Some countries (Syria, Libya, Somalia, Egypt, Turkmenistan) have no vaccination programs as of 2024

## Browser Compatibility

- **Requires**: Modern browser with WebGL support
- **Tested**: Chrome 120+, Firefox 121+, Safari 17+, Edge 120+
- **Mobile**: Fully responsive, touch-friendly controls

## Performance

- **Data points**: 146 countries
- **Layers**: 3 (circles, 3D extrusions, labels)
- **Rendering**: 60fps auto-rotation maintained
- **Metric switching**: <50ms update time
- **3D toggle**: Smooth 1-second transition

## The Bigger Picture

### WHO Cervical Cancer Elimination Strategy

The World Health Organization has set ambitious goals for 2030:
- 90% vaccination coverage for girls by age 15
- 70% screening coverage for women
- 90% treatment access for detected lesions

**Current progress**: Only 22 countries are on track to eliminate cervical cancer as a public health problem by 2030.

### The Promise

If universal HPV vaccination were achieved:
- **311,000 lives saved annually**
- Cervical cancer could become rare worldwide
- The first cancer potentially eliminated through vaccination
- Profound reduction in gender health inequity

### The Challenge

This visualization makes visible the gap between what is possible (near-elimination of cervical cancer) and what exists (vast global inequity in vaccine access). The technical capability exists; the political will and resource allocation do not.

## Development Context

**Iteration 14** in the progressive Mapbox learning series focuses on:
- Multi-dimensional correlation visualization
- 3D extrusion techniques for burden representation
- Semantic color theory for health equity narratives
- Dual choropleth encoding (size + color independently selectable)
- Gender health and global equity storytelling through data

**Previous iterations** explored:
- Basic globe setup and interpolate expressions (Iterations 1-3)
- Multi-layer composition (Iteration 4)
- Data-driven styling and match expressions (Iteration 5)
- Various thematic visualizations (Iterations 6-13)

**New techniques in this iteration**:
- Fill-extrusion layer with toggleable visibility
- Case expressions for conditional highlighting
- 4×4 metric matrix (16 visualization modes)
- Automated camera pitch adjustment
- Health equity narrative through visual encoding

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**Visualization Goal**: Make visible both the medical triumph of HPV vaccination and the moral failure of inequitable global access, inspiring action toward universal coverage and cervical cancer elimination.

**Dedicated to**: The hundreds of thousands of women who die each year from a preventable cancer, and the public health workers fighting to change that reality.
