I want to put down my thoughts on the 50% virus propagation rate now claimed by the Authorities.
First a teentsy weentsy bit of maths: Here’s how propagation works. A group of people have the virus and, on average, each passes it on to ρ more people. If ρ is less than one, we expect the virus to eventually run its course. (I’m assuming there are sufficient uninfected individuals to pass it on to or it will run its course even sooner). The average number of people affected by each initial carrier will eventually be ρ / (1 – ρ). (NB: this formula is only valid when ρ is strictly less that 1).
So, for instance, if ρ = 0.8, one initial carrier will affect 0.8 others, who will affect 0.64, who will affect 0.512, who will … and so on until ultimately a total of 4 people will be affected. And that’s all! Finito!
So, if ρ = 0.5, as claimed, the total affected by one initial carrier will be one more!
0.5 + 0.25 + 0.125 + … = 1
Here’s a little diagram illustrating how the one person on the left eventually produces one further infected person on the right.
This means that of all the people currently infected, assuming they have not yet had the indelicacy to infect another, they will still only infect one more.
Do you believe the claim that the rate is only 50%? We can think of it an an iceberg where we don’t have all the information but we are making a prediction that in spite of what we don’t know, we don’t expect to have any more that twice as many cases in total as those already in existence. This is a very confident claim, suggesting that the pandemic is virtually over.
Asynchronists 