The deadly model is all very well and good, but actually totally deadly diseases are fortunately fairly rare. It is much more usual for some percentage of people to be immune to the disease, or catch it and recover, becoming immune afterwards.
We've now set the scrollbars to 50 across the board. What you should see now when you add people is that roughly half of them are immune to start with (blue). In addition, some people survive to become immune (blue) rather than dying (gray).
Change the levels of people immune to start with, and the levels recovering to be immune, and see how this changes the spreading rate.
Green circle = Susceptible person
Red circle = Infected person
Gray circle = Dead person ('dead' dead, not un-dead!)
[Blue circle = Immune person (none of these yet)
Questions:
What kinds of effects to these different options have?
What settings would you give these options for the following diseases:
Given the people here move randomly and real people don't, do you think immunity will be more or less important in the real world?
Finally, go to Part 4 where we'll the model in more detail and how we might show and compare some of these ideas.