# COVID-19 in the UK

Up until recently, I used a couple of resources (i.e. one, two) for tracking an updated number of confirmed covid-19 cases.

Given the high speed at which the virus is spreading, I was having a difficult time intuiting the shape of this growth. For example if today the total number of confirmed cases for covid-19 in the UK was 500, I could not remember if yesterday it was 450, 400, or 200.

Thankfully someone is publishing this data as a timeseries database. I am currently living in London, so I decided to chart the daily number of confirmed covid-19 cases in the UK to better understand what is happening.

## Back of the envelope predictions

From what I have read, a population where 60% of its constituents have been infected with covid-19 and have recovered is said to have "herd immunity". Once a population has herd immunity, the rate at which the virus spreads decreases.

Roughly 60M people live in the UK; 60% of 60M is around 40M. Before a population reaches "herd immunity", the total number of true covid-19 cases doubles every five days. Therefore in fifty days you might expect the number of true cases to be 1000x larger than what it is today.

So if you think the total number of true covid-19 cases today is 40,000 then you might expect the rate of growth to slow down in a little less than two months.

Thank you for reading.