This is an interesting topic which I am sure a lot of people will be wanting to have answered…..however the short answer is nobody knows! However we can say when it’s slowing down and what the final number might be at that point. So let’s look at two sources of information.
1st, Public Health England has just started to produce a running total of all UK cases which provides a good source of statistical information. You can find it here. The most important thing for us is that it gives the daily number of cases.
2nd, I invite you to watch the following 9 min You Tube film and then together we can make some deductions.
Now, I am not up on my maths myself, (perhaps someone is in Stinchcombe) but having watched the video we learn basically that the number of the population infected follows an exponential curve at the start and then slows down until the Average Growth Factor drops below 1 or “The Inflection Point” and from that point the total number of cases in the UK will top out to be around double the number at “The Inflection Point”.
At present however we are far, far from this point and the Growth Factor seems to be averaging around 1.28. If that high rate remains the case, the total infected by 31st March in the UK would be over 75K.
See the chart below, the figures are all estimated after 13 March but on the right side are the actual numbers of cases in Italy up to-days date, but offset in time to try and match the growth curve in the UK. You will see it matches almost exactly but that without change, we are around 11 days behind Italy.
|Date||Total Cases||Change||Growth Factor||7 day Avg||Total Cases||Change|
|14/03||1056 E||259 E||1.28||1.28||2036||335|
|15/03||1387 E||331 E||1.28||2502||466|
|16/03||1810 E||424 E||1.28||3089||587|
|17/03||2352 E||542 E||1.28||3858||769|
|18/03||3046 E||694 E||1.28||4636||778|
|19/03||3935 E||888 E||1.28||5883||1247|
|20/03||5072 E||1137 E||1.28||7375||1492|
|21/03||6528 E||1456 E||1.28||9172||1797|
|22/03||8391 E||1863 E||1.28||10149||977|
|23/03||10775 E||2385 E||1.28||12462||2313|
|24/03||13828 E||3053 E||1.28||15113||2651|
|26/03||22737 E||5001 E||1.28|
|27/03||29138 E||6402 E||1.28|
|28/03||37332 E||8194 E||1.28|
Obviously we don’t want this to happen, but remember 75K is still only 0.1% of the population. We also saw watching the film that the increase in the number of cases on a given day is a direct multiplication of the Average number of infected people we are exposed to each day times the Probability of each exposure becoming an infection. I.E. The fewer people you meet plus the more careful we are with hygiene will directly effect the growth factor.
This of course is why other countries have gone into lock-down and why next week will be crucial here in the UK. – Remember, infections received today show up in 7 / 14 days time.
So keep an eye on the average 7 day growth factor, when it drops below 1.00, you know we are on the way to turning around the infection in the UK.
Lastly remember, what all the above does not show is the large percentage of people that catch Coronavirus and quickly get better without showing up on the statistics. This could be as high as 80% of those infected so by the end of the month 375K people could be infected. But this is still only 0.05% of the population.