Masking, models and reality (part 5)
What do SEIR models predict about interventions like mask mandates and how do those predictions compare to what actually happened?
This is the final post in a short series of posts:
Part 2: What do SEIR models predict will happen if R₀ changes?
Part 4: Modelling the effects of a mask mandate with 30% compliance using SEIR
Part 5: Comparing mask mandate model predictions with the real world
In the previous parts we have looked at how the models predict that all interventions that have an effect of reducing the impact of an epidemic will increase the full width at half maximum of the wave of infectious people and for parameters in the neighbourhood of where some people suspect COVID-19’s parameters are, if even 30% of people complied with a mask mandate that reduced their risk of infection by 95% then we expect the Full Width at Half Maximum to almost double… which on the face of it looks like we should have no problem showing the benefits of mask mandates…
Comparing mask mandate model predictions with the real world
In Europe, for most of 2022, Germany has had a FFP2 mask mandate in shops and public transport. If you are wondering what the difference is between FFP2 and N95 the answer is very little. A FFP2 mask must capture at least 94% of all particles above 0.3µm while a N95 mask must capture at least 95% of all particles above 0.3µm.
Conversely, the Netherlands has not had a mask mandate and most people have been very lax in masking… so if masks have a significant effect we expect to see the German waves to be maybe twice as wide as the waves in the Netherlands…
Now the waves might be different heights, but the widths to the eye look to be the same. Using photoshop, I can vertically stretch the Netherlands part of the graph to make it taller and let us compare more directly…
From the above graph we see the full width at half maximum is approximately the same for the mid-July 2022 wave (note: you measure the height from the baseline, not from zero)
Things do not get much better when we look at the mid-October 2022 waves as they too are similar widths for Germany and the Netherlands… if anything this wave is slightly wider for the Netherlands indicating that they might have done something different from Germany that may have slightly reduced infections in the Netherlands…
Now the Netherlands and Germany are a useful pair of countries to test the model with because they are geographic neighbours with significantly different masking regimes…
There is an old phrase: “the exception proves the rule”. To understand the meaning of this phrase it helps to know that the old meaning of prove was what we understand now as test. In other words, the exception tests if the rule is valid.
In science, I only have to provide one counter-example that your theory cannot explain in order to show that your theory is wrong. I don’t have to provide an alternative theory. I certainly shouldn’t need to point out that masks designed to catch particles 0.3µm or larger maybe do nothing about virions that are maybe at most 0.1µm.
Comparing the Netherlands and Germany says that FFP2 mask mandates do not have a measurable beneficial effect and given there are negative effects to masking such as increased bacterial and fungal exposure one has to wonder the wisdom of mask mandates.
What do you think?