One of our most popular articles is this one explaining the dynamics of the virus in non-mathematical terms. Now we have gone one better with this animation.
Click here to view.
By Mark.E.Thomas | April 19th, 2020
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4 comments so far
If there is no herd immunity doesnt the model have to take on a more circular rather than linear approach?
Yes. If there were zero acquired immunity, then the Recovered vessel would need to feed straight back up to the top left vessel (which would need to be renamed Susceptible).
Your model could be used to illustrate a few extra concepts:
The tap’s setting could be related to the number of infected fed back through an amplifer with value ‘R’.
Or more fancy, a series of amplifiers containing the roots or R, which itself is the product of variables representing infectiousness, contact frequency and susceptibility.
You could also have a separate pipe as a shortcut showing the effect of a vaccine…
The model is a good one, but in the case of the UK, the vessel which is most susceptible to a lack of capacity is the ‘severe’ vessel. The impact of this filling up with covid cases is that the NHS runs out of ICU capacity to treat other ailments and emergencies. So a better model would show the (time-delayed) impact of restrictions slowing down the rate of flow to cases, and the fact that severe cases will continue to rise for at least 2 weeks after any given additional restrictions are implemented.
If only around 8% of the UK population are currently in the ‘recovered’ pool, it would also be worth scaling the model further to show the impact on how many times we may need to cycle through tighter restrictions to ensure NHS capacity is not exceeded, before there is a reasonable chance of reaching herd immunity. Probably another 2-3 years if we do not breech NHS ICU capacities in a meaningful way, and there is no vaccine. Shorter, obviously, if effective vaccine/s and uptake level us achieves.