Year 11 / Infectious disease and epidemiology
Follow the outbreak.
Infectious disease spread depends on contact, the probability of transmission per contact and how long an infected person remains infectious. An effective reproduction number above one indicates growth under the model; below one indicates decline.
Vaccination, isolation and reduced risky contact can lower the effective reproduction number. Real outbreaks also depend on mixing, immunity, behaviour and uncertainty; one number is a simplified summary, not a guarantee for each person.
Disease transmission
Explore: Adjust contacts, transmission probability and duration to cross the R_eff = 1 threshold.
A model has 4 risky contacts per day, 0.1 transmission probability and 5 infectious days.
- Multiply 4 × 0.1 × 5 to estimate 2 secondary cases.
- Halving contact rate would bring the estimate to 1.
Assumed knowledge
Multiplication and proportional reasoning.
Learning checkpoints & source
YOUR LEARNING CHECKPOINT- Interpret transmission using a simple reproduction number.
- Predict how interventions reduce spread.
READY TO TRY IT?