Simulating a PID in a DAE - how to simulate a DDAE?

I used the example of the SIR model I linked above and a vector of constant lags summed over like in this example

I am not sure what you mean by Ix = Integral(x). I searched in the DifferentialEquations docs and github page and can’t find anything like that. The closest thing I found was Integrals.jl, but it doesn’t seem to have any examples that use DEs.

If you meant something specitic, then I would appreciate clarification. Otherwise, I have a working solution now.

thanks for your help