Results
As of the 24th April 2020, the number of a confirmed case of COVID-19 in England stands at 104,565 with 16,996 deaths. These covered a total recorded population of 60 million.
Figure 1 shows the reported new cases of COVID-19 have peaked on the 8th April and with reported deaths from COVID-19 which lags new cases by a week have also peaked.
Analysis for 19th April 2020 (5 days before the latest new cases presentation) shows the national RADIR was 0.81 with ΔIR at -0.03. In figure 2, the RADIR is plotted against time, highlighting that the daily R-value breakthrough below 1 was also achieved on the 8th April 2020.
The results of this analysis as shown in Figure 2 show a steady level RADIR below 3 before the 24/3/2020 lockdown and then a steady fall RADIR after that. The current infection RADIR has stabilised at around 0.8. However, given the strong likelihood that the virus will become endemic, a reproductive rate of 0 is unrealistic. Nevertheless, keeping the ongoing RADIR value below 1 is an opportunity to reduce rapid re-emergence adopted by the UK Government.
Figure 3 shows the differences in UTLAs of RADIR and ΔIR. This shows that there is a wide difference between UTLAs with over 30 of them still with infection rates above 1 but decreasing, while other regions already well below 1 and decreasing more slowly. There remain some regions where progress is slower. The inclusion of the number of reported cases/1,000 population quartiles show that those regions with the highest cases/1,000 population now have the lowest infection rates, suggesting there may be a relationship between these two factors.
The stepwise regression of the local UTLA factors to RADIR showed that only one factor total reported cases/1,000 population was significantly linked. In Figure 4, the regression, weighted by local UTLA population, had an r2=0.22, p value<0.0001 and the standardised beta of -0.42. Of note here is that the analysis is carried out 5 days before the latest data as, due to the incubation period, that is when the relevant infections would have taken place, and the latest data itself is also subject to ongoing updates.
The regression results in an equation RADIR = 1.06 - 0.16 x Current Total Cases/1,000 population. The reported cases are an unknown fraction of the total community cases. However, one can see that without any reported cases (i.e. no reduced community immunity) a UTLA would have RADIRof 1.0 - thus the implementation of social distancing has delivered a substantial reduction from the historic R with low number of existing cases at 2.8 (figure 2).
If this relationship is linear then extrapolation (See Figure 4) shows zero RADIR being achieved at 6.6 reported cases/1,000 community population. Therefore, to achieve full population immunity, this is equivalent to 150 community cases for each reported case. Total reporting of 400,000 confirmed cases would be expected if the total population of 60 million achieved increased immunity. This also suggests with current 105,000 reported cases that 16.1 million (26.8% of the total population) have now been infected.
Applying the 150 difference between community infection and reported cases can also be used to examine mortality. The ONS reported between 1 and 31 March 2020, there was a total of 47,358 deaths. Of these, 3,912 deaths (8%) were reported to have involved the coronavirus (COVID-19)). There were a total 12,288 reported cases of COVID-19 up to 5 days before the end of March; this, according to the above factor (150), is equivalent to a community infection of around 2.0 million people. This reflects a mortality rate of 0.2% in the total infected population. If this rate is applied to the total 60 million population then up to 120,000 are at risk of dying.