Simulating an epidemic
3blue1brown is a channel about animating math, in all senses of the word animate.
The source code for this video is visible at the link below, but the, er, awkward part is that it was made on a branch of manim where I'm reworking a lot of other things and have yet to work out all the kinks or add any documentation, so I'm not entirely sure how easy it will be for others to get running. In either case, you should be able to easily see how all the simulations worked.
Honestly, given that the code for that video is meant for demo purposes, and not meant to reflect the true data of COVID-19, if you want to apply these ideas to the current situation I'd recommend looking for more professional epidemiological modeling tools that are less centered around animations and pedagogy and more focused on accurate predictions. For example, the Institute for Disease Modeling has a lot of models free for people to look at and play with.