I wanted to explore how a disease might spread through a population and what factors would affect it. I couldn't find quite what I was looking for so figured it was a good opportunity to dive in to learning D3. It's still a work in progress as I have time to add new features and squash any bugs.

Epidemiology Visualization

Since I started on this in early March 2020 I have found several other very well done visualizations.

Washington Post Virus Simulator that starts with very basic simulations and then adds in more factors like social distancing.

Pandemic Visualization by 3Blue1Brown. Excellent visuals, clearly explained, and he tries lots of different scenarios.