I have been following the remarkable COVID-19 pandemic charts posted by @janvda here and here, and I wanted to be able to make comparisons with predictions from contagious disease models and explore a few "what if" scenarios. The standard models, known as compartmental models, are described in some detail in Wikipedia. There are many implementations available on the internet, but I felt I might learn something by building flows in Node-RED. The results are in this GitHub repo. One tab shows a side-by-side comparison of two model runs, with the model type and parameters selected independently. The other tab shows the result of imposing or modifying interventions (lockdown or social distancing), defined by changes in the reproduction number (R0) at specified times.
It goes without saying that these flows should not be taken seriously as models of the current pandemic -- they are strictly educational toys. Because this is work in progress and at an early stage, I have not posted it to the NR Flow Library. Comments, suggestions, and bug reports are welcome here or on Github.