@zebedee

The maths is very basic but the modelers seem to fall into two groups: Those who understand the maths but dont understand the bio-science; and those who understand the bio-science but fail to understand the maths. The **∩ **for these two sets is almost a null set. Very very few seem to understand both sides. Which is vital for a useful mathematical model.

The hand-waving of the bio-science people in epidemiology is that they either use maths without understanding the limitations and underlying assumptions of what they are using, or else simplify to the point of irrelevance because the maths required for the model they are creating is beyond their level of expertise. Very few progress beyond stock use of standard R packages. For accurate models of this type you are very much into PDE territory.

The maths people are worse in that they usually stick in key values in their models without doing even the most basic research of the relevant medical or bio-science literature. Really basic stuff. The criminal incompetence of Ferguson group at Imperial has been discussed here before but for me the defining moment was the model used as the basic for the shutdown in Lombardy and then all of Northern Italy in February 2020. Which started this whole mass hysteria and catastrophe in Europe.

The model assumed an At Risk population of 100% while the Hong Kong data already showed it was only a small subset due to high cross immunity. And the model assumed an asymptomatic rate of 10%. Not the 50% to 70% that was already clear. The clinical pathology of SARs CoV 2 was following the same pattern as the other human corona viruses. Stick in realistic values and what you have is a very bad short term viral pneumonia epidemic. Which is what happened.

All the horror stories you heard from Italy at the time, spring 2020, were due politics and Italy's socialized medical system. So no surge capacity and the initial refusal of other regions to take overflow ICU patients from the North. The medical system collapsed in Lombardy, Piedmont and Emilia-Romagna but was below capacity in most other regions. And that simplistic and wrong model had a lot to do with it. When added to the toxic brew of local politics.