Today we have a headline from ToVima which contains the word “explosion” with regards to the number of COVID19 cases in Greece.
What the entire article fails to mention is that this “explosion” in cases comes on the same day there has been an “explosion” the number of tests.
On the 23rd of February, 2147 new cases were reported, the 20th of February saw 1424 new cases.
This seems like a huge jump until you consider the number of tests. 56K for the 23rd vs 43K for the 20th. A 50% increase in cases versus a 30% increase in testing.
In reality, if testing numbers were constant, this “explosion” would be equivalent to 1653 cases.
Is 1653 COVID19 cases in Greece, in a single day, unusual?
Actually no, it is actually slightly better than the previous two days.
Looking further back, Greece increased the lockdown restrictions on the 5th of February from already restrictive levels. At that time the ratio of tests to cases was around 35. Since then we have seen this number decrease, a negative sign. The situation appears to be getting slightly worse but this happening during a period of tighter restrictions, restrictions which are supposed to be improving the situation.
If we assume a 10 day lag from the effect of these tighter restrictions taking effect we should see an improvement in the COVID19 test to case ratio, but do we?
In a word no, on the 15th of February (10 days after tighter restrictions brought in) we see a test to case ratio of 17, suggesting twice as much prevalence of the virus compared to when the restrictions were less tight.
If we take an average from the 15th of February until today, the 24th of Feb, we see an test to case ratio of around 30 and in the last three days we see an average of around 22.
In short, the longer the restrictions are in place the worse the situation seems to be getting.
COVID19 Greece – The track record of restrictions
Time and time again we see when restrictions are brought in or tightened, the virus situation in Greece deteriorates
Can it be a coincidence?
The 18th of January saw people being able to enter shops for the first time since December, what did we see on the 28th of January (10 days later) with regards to tests per case?
We saw 48 tests per case on the 28th of January vs 103 on the 18th of January.
If we take an average over 5 days, 18 Jan-23 Jan and 28 Jan-3 Feb, we see around 65 for the former and 53 for the later. A 20% increase in prevalence, sounds negative but is it?
I have written previously how the composition of the testing has changed namely the increase in the proportion of the tests that are PCR. This will play a part in the increase of the positivity rate. We would expect more positive tests with the PCR test.
Taking test type into consideration and looking solely at the tests to case ratio we can say that things are largely unchanged, however we also need to look at deaths.
Why? If a harmless virus is circulating is does not make any difference if more people have it.
To compare tests, cases and deaths we have the Lethality Index.
What does the Lethality Index say about the effect of this latest lockdown versus the period with slightly less restrictions.
18th of Jan the number was 0.39. On the 28th of Jan the number was 0.23. We see a marked improvement in the Lethality Index with a relaxation in restrictions.
Can we confirm this correlation in the opposite direction?
Does the Lethality Index also increase when restrictions are tightened?
On the 5th of Feb we have a 7 day rolling average Lethality Index number of 0.33. On the 15th of Feb we have a number of 0.45.
We see a worsening in the Lethality Index when restrictions are tightened and we see an improvement in the Lethality Index when the restrictions are relaxed.
The number of tests can skew our perception of the COVID19 situation in Greece, the composition of test type can also skew our perception but when we bring tests, cases and deaths together into one number, the Lethality Index, the truth of the situation in exposed.
Going back to the headline, I believe it is misleading at best, no, COVID19 in Greece did not witness an “explosion” in cases relative to the number of tests. What we are seeing in the numbers is a very gradual worsening in the situation and this decline is occurring when restrictive measures are in place.
Until such time we see this pattern (of lockdowns appearing to aggravate the situation) we will continue to push for a relaxation in the name of saving lives and improving public health generally.