# Trying to make sense of the figures



## Brendan Burgess (11 Apr 2020)

More detail about the number of tests.  









						Covid 19: 25 more deaths and 480 new cases
					

The Department of Health has confirmed 25 more deaths from Covid-19 in Ireland, bringing the total number of deaths from the disease to 288.




					www.rte.ie
				




The total number of Covid-19 cases now confirmed in Ireland is 8,089.

Initially the department had announced a figure of 7,054 but revised that this evening to include test results from Germany.

The department said to date there has been 14,000 samples returned from German labs, of which 1,035 were positive.

When those figures are included it brings the total number of confirmed cases in Ireland to 8,089.


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## Brendan Burgess (11 Apr 2020)

OK. These were the figures before the correction.


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## Brendan Burgess (11 Apr 2020)

They actually tell you very little about the progress of the disease. 

On April 10, there were 480 + 1,035 cases confirmed. 

But these swabs were probably taken  7 to 10 days ago.   And the people got the infection  up to 21 days before that. 

The actual numbers of new cases in the population today could be a lot higher or a lot lower.  We just don't know.

We would suspect that with the physical distancing, the new infections are very low.  But we just don't know.

Brendan


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## Brendan Burgess (11 Apr 2020)

So the Department of Health should say something like 

1,515 people 
Who became infected with Covid between 1 March and 15 March 
Were tested between 10 March and the 25 March 
And we got the results back today to tell us that they were positive. 

Brendan


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## Oisin19 (11 Apr 2020)

They have to get on top of the testing ASAP. It’s quickly becoming an issue and could lead to people losing the faith! It’s also vital for the exit plan from these restrictions

It looks like they have it solved now with the new suppliers on board that can do 900k tests. Hopefully over the next week this gets sorted and we have a better picture of where we are at.

At least the death rate appears to be slowing as the amount of deaths seems to be level for the last week or so.


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## Drakon (11 Apr 2020)

The test numbers tell you nothing because it’s so arbitrary. 
The body count is the only true reflection, and the deaths per million. 
The USA has been doing a better job than Ireland in terms of DPM!


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## Brendan Burgess (11 Apr 2020)

Drakon said:


> The body count is the only true reflection, and the deaths per million.



Hi Drakon

But to plan ahead, we need to know whether the virus is still spreading or not.  The death count tells us only about the infection rate 20 days ago.

But I suppose if the death rate starts to fall, it will tell us that the infection rate started falling three weeks ago,

Brendan


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## llgon (11 Apr 2020)

I'm probably getting into semantics here Brendan but I think your summary has two errors so to make full sense of the figures I'm going to point them out.

1. The results of the tests processed in Germany have been coming in gradually for at least a few days and they have been announced daily. The department just totalled them yesterday and added them to the total of positive tests processed in Ireland.

2. The 480 figure yesterday were more recent tests processed in Ireland.



Brendan Burgess said:


> 1,515 people
> Who became infected with Covid between 1 March and 15 March
> Were tested between 10 March and the 25 March
> And we got the results back today to tell us that they were positive.



So my understanding is:

_"1,035_ people
Who became infected with Covid between 1 March and 15 March
Were tested between 10 March and the 25 March
And we got the results back _over the past few days_ to tell us that they were positive."

At this stage I think the number of confirmed cases is relatively unimportant, due to all the issues with the testing. Some of these issues were beyond the control of the authorities but I think they should have done more to keep the public informed on the amount of testing being done.  The way the figures have been presented over the past couple of days has also left a lot to be desired.


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## Drakon (11 Apr 2020)

There are four people in my house. 
My wife tested positive. 
I was sick for two weeks.
My son was sick for about five days.
My daughter was sick for one night.


The test figures would suggest one case. 
Common sense suggests three cases, and possibly four.


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## llgon (11 Apr 2020)

Brendan Burgess said:


> But to plan ahead, we need to know whether the virus is still spreading or not.



The current testing regime and figures will not help with this. Hopefully we will see a much better system in the next two weeks.


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## llgon (11 Apr 2020)

This is from the update released by the Department yesterday. When questioned repeatedly about it Dr Holohan could see no problem with the presentation of the figures:

"480 new cases of COVID-19 in Ireland have been confirmed. There are _now 7054 confirmed cases _of COVID-19 in Ireland.

Including test results which have been sent to Germany for testing (which may include tests from older cases) the total figure of those who have been diagnosed with COVID-19 in Ireland _now stands at 8,089_."

(Italics added)


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## Brendan Burgess (11 Apr 2020)

llgon said:


> At this stage I think the number of confirmed cases is relatively unimportant, due to all the issues with the testing.



Hi ligon

That is the point I was making. 

It is an unreliable figure based on inadequate testing carried out 10 days ago.

It tells us nothing about how the virus is spreading today. 

Brendan


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## Brendan Burgess (11 Apr 2020)

Drakon said:


> There are four people in my house.
> My wife tested positive.
> I was sick for two weeks.
> My son was sick for about five days.
> My daughter was sick for one night.



Hi Drakon 

How is your wife now? 

 Were you all tested and three of you came out negative? 

I had been in contact with a confirmed case and was "under the weather".  If I had Coronavirus, by the time I would have been tested , I would probably have recovered so I might have come up negative.  If I had got the results 10 days after the test, it wouldn't have told me anything about my health on that day. 

I presume that the test tells you only "You are positive".  Or does it tell you "You are very heavily infected and will be a few weeks before you are no longer infectious" ?

Brendan


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## Drakon (11 Apr 2020)

She’s fine, she’s back to work. Had one bad night where she’d difficultly breathing and considered calling the doctor, but our cases were mild.
I had been scheduled to have a test but after a week they changed the criteria and I never heard anything again.
My wife was the only one tested.
AFAIK she was told she was positive, that I was it, no further description.
She was meant to be re-tested five days after all symptoms cleared, and then a double check test again the day after that. But neither of those tests happened.
I assume I was positive as my symptoms were very similar to hers. Likewise with my son though his bout was shorter. My daughter, well, who knows. She was vomiting one night but may have been otherwise asymptotic.

I look forward at anti-body testing.


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## Brendan Burgess (11 Apr 2020)

Drakon said:


> She’s fine, she’s back to work.





Drakon said:


> She was meant to be re-tested five days after all symptoms cleared, and then a double check test again the day after that. But neither of those tests happened.



That is very interesting.  I presume that her doctor cleared her to go back to work? 

Is it that simple.  5 days without symptoms means that you are no longer infectious? 

Brendan


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## Drakon (11 Apr 2020)

Nope, no trip to the doctor. Just went into work again five days later.


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## llgon (11 Apr 2020)

Brendan Burgess said:


> Is it that simple. 5 days without symptoms means that you are no longer infectious



*When you can stop self-isolating*
Only stop self-isolation when both of these apply to you:


you have had no fever for 5 days
it has been 14 days since you first developed symptoms









						Self-isolation (stay in your room)
					

Find out how to self-isolate (stay in your room) to help stop the spread of COVID-19 (coronavirus).




					www2.hse.ie


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## Brendan Burgess (12 Apr 2020)

I am now convinced that the only reliable and meaningful figure is the number of deaths.  The rest is noise as the new cases figures show.





The best estimate we can get for the true number of new infections is by working back from the number of deaths. 

If we assume that the death rate is 2% , it means that we had 700 new cases about 19 days ago.  (I might not have the assumptions correct, but you get the methodology)

We should see the death rate falling if the restrictions introduced 16 days ago are having an impact. 

Brendan


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## SPC100 (12 Apr 2020)

Iirc from other studies cfr is estimated to be more like .35% when counting asymptomatic and mild experiences. I.e. lots of folks that will not have turned up in our testing.


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## SPC100 (12 Apr 2020)

Even deaths can suffer from attribution issues and/or lack of testing. But I agree it is the most reliable number for trend.

although as I mentioned elsewhere it is a lagging rather than leading indicator.


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## mathepac (13 Apr 2020)

I've been saying since the start of this health crisis that the numbers we are being shown are all just hooha or maybe  Holohanha, a new term for all the mathematical masturbation the modellers and graphics studios are getting into.

The  only meaningful numbers are:

Number of samples taken, daily and total
Number of samples tested, daily and total
Number of people re-tested, daily and total (one negative test does not mean never being at future risk)
Days between sample taken and test completed, best case, worst, mean
Days between test completed and results returned to subject best case, worst, mean
Number of positive tests, daily and total
Numbers admitted to hospital, daily and total
Numbers discharged from hospital, daily and total
Number of deaths, daily and total
Useful Data:

PPSN
Home eircode
Number in household
Work eircode
Employment classification (health-care worker [medic, nurse, physio, hospital porter, health-care assistant, medical admin, contractor to hospital/medical centre, medicall admin,etc]}
Forecasting peaks and all that stuff is just more Holohanha; we'll only know after we've passed the peak.

Any thoughts?


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## Brendan Burgess (13 Apr 2020)

SPC100 said:


> Iirc from other studies cfr is estimated to be more like .35%



That is very interesting and it would be useful if you could find a source.

But my general point is that it is only when we get a sustained reduction in the number of Covid deaths, will we know that the virus stopped increasing 19 days earlier. 

Agree on the attribution issues. However, we could assume that the error in attribution is constant. 

Brendan


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## SPC100 (13 Apr 2020)

see disambiguation in this article between case fatality rate, infection fatality rate, crude mortality rate.









						Mortality Risk of COVID-19
					

Our interactive data visualizations that show the case fatality rate in each country are updated daily.




					ourworldindata.org
				




If estimating number infected (in the past) from (today's) deaths the cfr is not the correct number to use.

I was researching at the time how the overall death rates had changed since covid, in an attempt to avoid attribution issues.


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## SPC100 (14 Apr 2020)

Preliminary German Study Shows a COVID-19 Infection Fatality Rate of About 0.4 Percent
					

Preliminary results are out from a COVID-19 case cluster study in one of the regions worst hit by Germany's coronavirus...




					reason.com
				




Over the last two weeks, German virologists tested nearly 80 percent of the population of Gangelt for antibodies that indicate whether they'd been infected by the coronavirus. Around 15 percent had been infected, allowing them to calculate a COVID-19 infection fatality rate of about 0.37 percent. The researchers also concluded that people who recover from the infection are immune to reinfection, at least for a while.


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## SPC100 (15 Apr 2020)

406 deaths /.37% ifr estimates that 109729 were infected.


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## Brendan Burgess (15 Apr 2020)

Hi SPC 

What do those figures represent? Are they from the German study? 

In calculating the death rate, would we not need to see a full cycle? 

For example, out of everyone who got infected in February, they have either fully recovered now or died. 

Brendan


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## SPC100 (15 Apr 2020)

They are current total irish deaths to date divided by the infection fatality rate (from the german study).

This gives an estimate of how many people in Ireland were infected.

Obviosuly we don't know what the IFR is in Ireland, if it turns out to be higher, less people would have been infected.


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## Brendan Burgess (15 Apr 2020)

Ah, I see. 

So 19 days ago, say 27 March, you have worked out that there were 110,000 people infected compared to the 2,121 confirmed cases figure published by the HSE.

Brendan


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## Seagull (15 Apr 2020)

Bear in mind that Germany didn't have widespread BCG vaccinations, which are thought to have a signifcant impact on mortality rates.


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## odyssey06 (16 Apr 2020)

A breakdown of the figures by current cases in what hospitals has been released, although with more breakdown by county.








						This report from the HSE shows the geographic spread of Covid-19 cases in Ireland
					

Beaumont Hospital in Dublin was treating the largest number of patients with Covid-19 in Irish acute hospitals last night.




					www.thejournal.ie


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