This model simulates the infectious disease outbreak in which the viral transmissibility evolves and breakthrough infections occur. It allows students to compare the maximum active cases and total deaths of an outbreak when 1) viral transmissibility mutation is present and absent and 2) breakthrough is present and absent. They can also investigate these scenarios at different vaccination levels.
Grades: 9-12; Intro Biology
HOW IT WORKS
The model starts with a population of susceptible (green) and vaccinated (blue) people if the vaccination rate is above 0%. Once an infected case (orange) appears in the population, it will pass infectious disease to one of the susceptible people nearby (within a radius of 1.5) at the defined original transmission rate. The infected people can transmit the disease for 14 days. No isolation or quarantine is considered in this model. By the 15th day of being infected, the infected people either die (disappear from the model) at mortality of 10%, or recover and become immune (blue).
When the mutation is enabled, some viruses' transmissibilities may mutate randomly. For example, the strain with the transmissibility of 50% may become more transmissible, e.g., 75%, or less transmissible, e.g., 30%. The infected person will infect the next susceptible person at the new transmission rate.
When breakthrough infections are enabled, the vaccinated or recovered people can be infected again (magenta color). They will be infected by the original strain at a low chance, about 1-2%, which is still much higher than the reality. But they have a higher chance of being infected by the mutated strains.
A constant mortality (10%) is used to simplify the model.
HOW TO USE IT
1. First, choose the factors, such as population size, original transmission rate, etc.
2. Input the Time to run the model.
3. Click on Set up/Reset, then +1 Infected Case and then Run/Pause. The number of days represents the duration of the outbreak.
4. Observe the infection changes in the population in the plots and monitors.
5. Use Run one day to run the model in a controlled way and collect day-by-day data.
6. Use Default Settings to retrieve the default settings.
THINGS TO TRY
There are so many things you can try in this model. Here are only very a few quick ideas:
How does mutation affect the outbreak duration, max active cases, and the number of breakthrough infections?
How does viral transmissibility evolve over an outbreak? Do you see any patterns when you use different starting transmission rates, i.e., low, medium, and high?
What factors may affect the number of breakthrough infections?
How do the breakthrough infections affect outbreak duration, max active cases, and total deaths at different vaccination levels?
Dr. Lin Xiang (lin.xiang@uky.edu) created this module at the University of Kentucky in 2022. If you mention this model in a publication, we ask that you include the citations below.
Xiang, L. (2022). Infectious Disease Outbreak-Mutation and breakthrough infections. Department of STEM Education, University of Kentucky, Lexington, KY.
Questions? Comments? Email us.