It is said you can divide the British population into those who trust The Chancellor of the Duchy of Lancaster and those that don’t. However whichever side you are on, I think you can agree that the best Teachers have had to go on is a vague statement that they should start bringing back children on 1st June. There are no data that I have seen which can be used as evidence. So I am disappointed to give the first public model of the risks involved in going back to school. My working out is going to be riddled with false assumptions. I apologise for inconsistent rounding before the final stage of the calculations. This is due to the fact the numbers are all very speculative and all I want to do is create is a polemic about how we can calculate the risk.
Isle of Sheppey has approximately 3750 primary children. For the only school on the island that I could find with the proportion per class they are evenly spread out through the age range, so 7 groups and 3 going back equals 1600. With 1 adult per 10 children this gives about 1800 souls.
Now here come some more big assumptions. Given an r of about o.8 and 208.1 (a degree of accuracy I would not use) per 100,000 in Swale confirmed positive and also 40 % of cases asymptomatic. I will assume the 208 are self-isolating but they will have passed it on to 0.8*208 = 166
208/60*40 =173 these 173 are still at large and could have passed it on to 0.8*173 = 138
For a total of 166+173+138 = 477 per 100,000 gives 477/100000 * 1800 = 9 infections in the new school population.
This actually nicely works out as 1 per school. But as the schools are different sizes I will work it out per class of 10. 10 given the size of a classroom, is the only number I think a possibility of non-transmission could occur.
So 9/160 = 0.06. So 6% of classes would have an infection. Another big assumption, that of passing it on to your child or teacher in the month, say 20%, this gives a 0.06*0.2= 0.012 chance of your child or teacher catching SARS CoV-2. 1 in a hundred. Now this risk will have to be weighed according to your family. I.e. ages, risk groups etc.
For me a 55-year-old male. 246,406 confirmed positive with 40% asymptomatic gives 410,676 cases. In my age group 2547 deaths gives 2547/410676= 0.006 chance of dying if infected. In this simple example I will ignore getting significant organ damage.
So 0.012*0.006 = 0.000072 chance of death in that month due to Covid 19
What does this mean? Risk of death UK in a year driving 0.000059 so about an order of magnitude (12) more risky. Although better than when my partner is driving. As the odds of dying in a vehicle accident are already considered high, these odds do not seem good. http://www.bandolier.org.uk/booth/Risk/trasnsportpop.html
Since completing these calculations I think it is interesting that I now have some degree of knowledge about the risks. I am also feeling a sense of shame that I have had to work it out on my old Casio rather than get the data from our Government.