Generally, that’s why I don’t write about theoretical models. They tend towards simplicity to the point of absurdity. The old quip that “some are useful” neglects the antipodal “most are not useful”, and, as we have seen with the coronavirus and climate change models, can blur or even obscure people’s world views to the point where they become dangerous, society-devouring fanatics.

But a couple people pointed out a paper from David Fisman titled Impact of population mixing between vaccinated and unvaccinated subpopulations on infectious disease dynamics, so I decided to give it a read.

The paper points out that “[s]imple mathematical models can often provide important insights into the behaviour of complex communicable diseases systems”. The model is definitely simple, but the insights garnered from it are about as useful as a modeller playing tic-tac-toe with himself. […]

The results are obvious because their entire model is just overly complicated algebra: the vaccinated get infected at higher rates when unvaccinated are presented and unvaccinated do worse with unvaccinated. This model is so insightful that I had to double check the credentials of the modellers because I could have sworn they were 3rd year undergraduate students.

If you set up the model in the same way, but assume vaccine effectiveness is strictly negative, then you get the opposite result.

Colby Cosh: Oh, for happier times, when what appeared in CMAJ a few hours ago was mostly ignored all the way through instead of half-digested…

h/t Hob, LindaL