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Ask HN: What chance that we wouldn't notice Covid19 if we hadn't tested for it?

4 points by mmmmmyumyum ↗ HN
I'd like this mainly to be a statistical/mathematical discussion based on the present data about Covid19. My question is: at what point in time did we know that Covid19 is killing more people than usual, based on the statistics?

My understanding is that the people that are counted as Covid19 deaths are those that were tested Covid 19-positive and then died from Pneumonia related health issues. However, Covid19 is possibly not the only Virus that can lead to Pneumonia and a person could be infected with multiple Viruses at the same time (I guess). Do we also test if a Covid19 positive person has the current influenza Virus in them, for example? Assume that all Covid19 patients also had the Influenza Virus in them, which might cause similar symptoms, then how do we know if a person should be counted towards "Covid19 death" or "Influenza death"? Or do we only count people to "Covid19 deaths" that only carried the Covid19 virus (and we specifically tested for other viruses)?

Also, I can't find base rates on the number of pneumonia deaths each year in Wuhan and the speed with which those are usually rising to determine how bad things really are. What are the models that are used to determine how bad things are when a new Virus is being found and at what point do we usually know that a newly found Virus is bad?

Overall I would like to know: how likely is it, that we would have never found anything being wrong just based on the people that die from Pneumonia related issues this year if we had never found Covid19? And with what confidence can we answer that question?

10 comments

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fcurts
> how likely is it, that we would have never found anything being wrong just based on the people that die from Pneumonia related issues this year if we had never found Covid19?

0%. Just read the reports from Wuhan and Italy. For example, citing from https://www.worldometers.info/coronavirus/country/italy/:

March 20 (GMT)

Italy: in the city of Bergamo, there were 108 more deaths in the first 15 days of March this year compared to 2019 (164 deaths in 2020 vs. 56 deaths in 2019) according to the mayor of the city Giorgio Gori. During this period, 31 deaths were attributed to the coronavirus (less than 30% of the additional deaths this year)

"There are significant numbers of people who have died but whose death hasn't been attributed to the coronavirus because they died at home or in a nursing home and so they weren't swabbed," said the mayor [source]

March 19 (GMT)

Italian army trucks form a long line in the center of Bergamo to transport the coffins from the Bergamo cemetery to cremation sites in other regions, as morgues can't cope with more coronavirus deaths

Obituaries in the local newspaper went from 1.5 pages (on Feb. 9) to 10 pages (on March 13)

mmmmmyumyum
You're comparing the number of deaths this year only to the number last year in the exact same time. What were the numbers in the years before? Comparing it to only one previous year doesn't allow to say that this is significant. With only one year we don't know the variance of this number. If less than 30% of the additional deaths this year were attributed to corona virus and 30% lies within a reasonable variance of this number over the years, then we wouldn't have noticed, or not?

Same for the remaining info: we don't know how many times it happened before (for example in the previous 20 years or so) that the morgues couldn't cope with more people dying from more people dying from pneumonia (for example during a particularly bad influenza season). That the corpses have been transported away by military trucks also doesn't tell us anything from a statistical point of view.

fcurts
> If less than 30% of the additional deaths this year were attributed to corona virus and 30% lies within a reasonable variance of this number over the years, then we wouldn't have noticed, or not?

You seem to be misinterpreting the statement, which says that even though "only" 30% of additional deaths are proven to be caused by the virus, the real number is likely higher.

It should be obvious that the situation in northern Italy is far beyond "reasonable variance". Google is your friend.

mmmmmyumyum
Well yeah.. it is likely higher.. let's say it's 50% or even 200%. That could still be within the variance. If you can't tell me what this variance is, then it is not obvious at all that the situation in Italy is far beyond "reasonable variance"! So far you have not given me any evidence that proves this statistically. Also you're misinterpreting the statement "it is likely higher" and assume this means it is definitely higher.
fcurts
Please stop spreading FUD. Thank you.
mmmmmyumyum
That's what I meant by "I want this to be a statistical discussion". I'm not spreading FUD at all. Those are all valid questions from a statistical point of view.

I'm definitely not spreading Fear. Fear is what is spread by the media when showing military trucks carrying away corpses and people subsequently assume that the situation is very very bad without asking for baselines.

mmmmmyumyum
Note: The two paragraphs in the link you replied with, are not evidence at all. For example the author also neglects the variance in the mortality rate each year. If they were evidence, then the author would deserve a nobel price in epidemiology.

On the other hand, here's a nobel price winner saying: "While many epidemiologists are warning of months, or even years, of massive social disruption and millions of deaths, Levitt says the data simply don’t support such a dire scenario — especially in areas where reasonable social distancing measures are in place."

This article concludes with “The real situation is not as nearly as terrible as they make it out to be,”.

https://www.latimes.com/science/story/2020-03-22/coronavirus...

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