Swiss Cheese Model Calculator
Analyze layered COVID-19 protection strategies
Protection Layers Configuration
🧀 Swiss Cheese Layers
Each layer is imperfect (like holes in Swiss cheese), but together they provide strong protection. Configure effectiveness and compliance for each layer.
Face Masks
Source control and personal protection
Social Distancing
Physical distance between people
Hand Hygiene
Regular handwashing and sanitizing
Ventilation
Air circulation and filtration
Testing
Regular screening and surveillance
Vaccination
Immunization protection
Isolation
Quarantine of symptomatic/positive cases
Contact Tracing
Identifying and notifying contacts
🌍 Environmental Context
📊 Situational Factors
Total number of people in the environment
How long people will be exposed
Swiss Cheese Model Analysis Results
Active Layer Contributions
Environmental Factors
Risk Analysis
📋 Recommendations
- Excellent protection strategy
- Maintain current measures and monitor compliance
🧀 The Swiss Cheese Model
📊 Layer Effectiveness Guide
⚠️ Risk Level Guide
Understanding the Swiss Cheese Model
The Concept
The Swiss Cheese Model, developed by Professor James Reason for accident analysis and adapted by Professor Ian Mackay for COVID-19, illustrates how layered defenses work. Each layer has gaps (like holes in Swiss cheese), but when properly aligned, multiple layers provide strong protection.
Key Principles:
- •No Perfect Layer: Every protection measure has limitations
- •Multiplicative Effect: Layers multiply protection, don't just add
- •Compliance Critical: Theoretical effectiveness requires proper use
- •Context Dependent: Environment affects all layer performance
Mathematical Model
The Swiss Cheese Model uses multiplicative risk reduction. If each layer blocks a percentage of risk, the residual risk is calculated as:
Residual Risk = (1 - Layer₁) × (1 - Layer₂) × ... × (1 - Layerₙ)For example, if you have:
Residual risk = (1-0.7) × (1-0.8) × (1-0.85) = 0.3 × 0.2 × 0.15 = 0.009 = 0.9%
This means 99.1% protection - much better than any single layer!
Protection Layer Effectiveness
| Protection Layer | Typical Effectiveness | Key Factors | Implementation Challenges |
|---|---|---|---|
| 😷 Face Masks | 50-95% | Type, fit, material quality | Proper fitting, compliance, replacement |
| 📏 Social Distancing | 60-90% | Distance, duration, activity level | Space limitations, social pressure |
| 🧼 Hand Hygiene | 40-80% | Frequency, technique, products used | Accessibility, habit formation |
| 🌬️ Ventilation | 60-95% | Air changes, filtration, outdoor air | Infrastructure, weather, cost |
| 🧪 Testing | 70-95% | Frequency, test type, follow-up | Cost, logistics, result delays |
| 💉 Vaccination | 50-95% | Vaccine type, timing, variants | Availability, hesitancy, updates |
| 🏠 Isolation | 90-99% | Complete separation, duration | Economic impact, mental health |
| 📱 Contact Tracing | 40-90% | Speed, coverage, technology | Privacy, participation, capacity |
Related COVID-19 Calculators
🏥 Important Health Disclaimer
FOR EDUCATIONAL PURPOSES ONLY: This Swiss Cheese Model calculator provides theoretical risk analysis based on simplified epidemiological models for educational purposes. Results should not replace official public health guidance or professional medical advice. Real-world effectiveness of protection layers depends on many factors including proper implementation, compliance rates, environmental conditions, viral variants, individual health status, and local transmission rates. The model uses general effectiveness estimates that may not reflect current scientific understanding or specific circumstances. Always follow current guidelines from health authorities like WHO, CDC, and local public health departments. This tool is intended to help understand the concept of layered protection strategies, not to guide specific health decisions. Consult healthcare professionals and official health sources for personalized guidance on COVID-19 prevention and risk assessment.