General Info
The Pandemic and the Epidemic Index
This research has been initiated by the following important question, motivated by the current coronavirus epidemic:
Can we estimate the efficacy of the medical and social preventive measures by a single number?
Alternatively, paraphrasing the journalist question from the UK press conference briefing, can we derive just one number to see whether the government social measures strategy is working?
An epidemic index (EPI) is proposed as an answer such a question.
Notation: EPI -Epidemic Index; ERI - Epidemic Risk Index.
EPI (UK)-index:
March - EPI
23 - 1.95 ;
24 – 1.82;
25 – 1.77;
26 – 1.82;
27 – 1.80;
28 – 1.84;
29 – 1.84;
30 – 1.79;
31 – 1.76;
April – EPI
1 – 1.70;
2 – 1.58;
3 – 1.51;
4 – 1.46;
5 – 1.50;
6 – 1.44;
7 – 1.31;
8 – 1.28;
9 – 1.20;
10 - 1.20;
11 – 1.06;
12 – 1.08;
13 - 1.12;
14 - 1.07;
15 - 1.08;
16 - 1.02;
17 - 1.06.
The EPI index is a type of the so-called "force of infection", the "current reproduction number R_0", or the "current transmission rates". The EPI represents the current rate of the epidemic spread.
The target is to get the value of the EPI index below 1.
From the table above it can be seen that the EPI(UK) numbers are going down, clearly showing that the UK government policy is working.
The EPI is derived via the epidemic stochastic modelling and the relative statistical data analysis.
It gives a slightly overestimated bound.
The threshold, or the change point, of the EPI falling below 1 is usually approximately 5 to 7 days after the peak of newly infected cases.
The EPI indices are computed for Belgium, Canada, China, France, Germany, Iran, Italy, Netherlands, Russia, South Korea, Spain, Switzerland, Turkey, and US.
Some brief info is summarised below.
Below is a list of countries, which have managed to put the infection spread under control, where the transmission rates fall below the value of 1 for at least 5 days (average infection period) and stay below this value.
China: Change(the change point) = Feb 10 to Feb 11 and Peak (the Peak of infection) = Feb 04.
South Korea: Change = March 5 to 6 and Peak =March 03.
Italy: Change = March 29 to 30 and Peak = March 21.
Spain: Change = April 04 to 05 and Peak = March 26.
Switzerland: Change = March 25 to 26 and Peak = March 20.
Germany: Change = April 05 to 06 and Peak = March 27.
Iran: Change = April 05 to 06 and Peak = March 28.
France: Change = April 05 to 06 and Peak = April 03.
US: Change = April 12 to 13 and Peak=April 11.
EPI (US)-index for the last two weeks in April 2020:
5 – 1.38;
6 – 1.33;
7 - 1.30
8 - 1.24,
9 - 1.17;
10 - 1.10;
11- 1.09;
12 - 1.05.;
13 - 0.98;
14 – 0.95;
15 – 0.93;
16 – 0.91;
17 – 0.9.
EPI (Canada)-index: April2020:
9 – 1.18;
10 - 1.07;
11 – 0.97;
12 – 0.96;
13 - 0.96;
14 - 0.94;
15 - 0.92;
16 - 0.97;
17 - 1.08.
Belgium and the Netherlands both displayed 2-3 days of the EPI index being close to or below the 1, but then moved to the above 1 zone. They are close to the potential victory.
It is well known that the epidemic with the reproduction number near zero can stay very long.
Even though the EPI UK numbers on Apr 10 - 12 are slightly smaller than those sent to you (due to the incorporation of extra UK government statistical information), they are still bigger than 1. That is why reporting the fact that UK has reduced their transmission rates to below 1 was premature.
Russia is an unfortunate example where the measures do not work at all. The EPI index from April 06 to 18 is varying between 1.81 and 1.59 and not decreasing.
18 April 2020