To give an understanding of how quickly COVID-19 is spreading, we analysed the relative change in the number of new cases per day across England. Due to reporting variations, a 7-day moving average was applied to this figure. A figure of 1.0 represents a constant rate of growth, for example 100 new cases per day, every day. A figure of 2.0 represents a doubling of new cases per day (for example day 1: 100 new cases, day 2: 200 new cases, day 3: 400 new cases, until day 10: 51,200). It is when the rate of change of new cases per day is above 1.0 that we have rapid growth in the number of cases.
The rate of change of new cases per day in England is decreasing.
Analysis of the rate of new cases per day for England demonstrates an initially rapid rate of growth (trending above 1.0). However since social distancing measures were brought into effect, these have decreased to a constant rate of growth of approximately 1.0. For the week commencing 20 April 2020 this trend decreased to below 1.0.
Analysis of regional rate of change of new cases per day indicates that for the week commencing the 20 April, the average number of new confirmed cases per day increased highest in Northamptonshire, Herefordshire, Bedfordshire and Cornwall.
Comparison of 7-day moving average rate of increase of new confirmed cases per day (until 27 April 2020) with Apple COVID-19 Mobility Report
Overlaying the data from the Apple COVID-19 Mobility Report we can identify that travel has decreased to around a quarter (based on the relative volume of directions requests per country, compared to a baseline volume on January 13th, 2020).