HS Lessons On Modeling Virus Spread I'd like to try teaching an online lesson to high school CS students on modeling the spread of a virus. Ideally it would be something that could be coded in a spreadsheet, Code.Org's Game Lab or App Lab, or in Unity.

I'd appreciate any pointers to how to get started – what are the important underlying concepts for students to understand, what are the minimal skills they would need to produce a "satisfying" model, what are the key variables that a model should incorporate?

Suggestions about how to get my own head around the field, or videos of modelers talking about their work, or articles would all be welcome.

Update:

First: many thanks for the great and concrete suggestions coming in, they really help.

Second: this is, or could be, a collaboration across disciplines – math, CS, health, social studies, and art / graphic design all have a role in developing and presenting a good model.

Third: clearly, in these times, this is a distance learning question as well.
Here are two resources that might be appropriate, but neither is a spreadsheet model. 

The first is a resource called Contagion that has just been created for the Greenfoot Java system (IDE plus resources). You can find it at the Greenroom. 

The second is a section on Simulation in a book called Polymorphism Companion. The book is actually the second volume of a pair and you might need the first one also Polymorphism: As It Is Played. They are both about using polymorphism, especially in Java. 

Both of these resources model a disease spreading through a population. They have various parameters you can set to get some realistic(ish) results. Think of a Disease interface, for example, with diseases of various characteristics implemented via polymorphism.