What is the denominator - Printable Version
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What is the denominator - BostonCard - 04-08-2020
The CDC is taking steps to find out.
https://www.statnews.com/2020/04/04/cdc-launches-studies-to-get-more-precise-count-of-undetected-covid-19-cases/
This is very much needed research, as it will finally answer questions such as what is the infection fatality rate, and whether there might be more herd immunity out there than we think.
Also, some much needed surveillance data:
https://www.cdc.gov/coronavirus/2019-ncov/covid-data/pdf/covidview.pdf
interestingly, on page 8, it shows the temporal trend in pneumonia and influenza mortality. You can see a big spike in deaths over the last couple weeks. Although deviations from the temporal trend have been observed (see winter of 2018), it does make you wonder if the big spike of deaths attributed to pneumonia and influenza at a time when these deaths should be going down are actually Covid-19 deaths.
BC
RE: What is the denominator - Snorlax94 - 04-08-2020
This is why I am so grateful for last weekend’s Stanford serum collection in SCC.
The CDC said they plan to start the nationwide test in the summer, and have no timeframe for the healthcare worker study.
The MercuryNews article said Stanford could be reporting results in weeks. We will hopefully begin to start learning more soon. I wonder if someone already has some very preliminary data. (They said they’d inform positive cases the next week, so they already may have data on how many cold/flu-like sick in SCC had Covid and how many asymptomatic people recovered without knowing it)
RE: What is the denominator - oldalum - 04-09-2020
L.A. announced it's going to randomly sample 1,000 people's serology to get an estimate of infection prevalence.
RE: What is the denominator - M T - 04-09-2020
Isn't the continuously collected blood supply a good sample for roughly estimating the number of asymptomatic + pre-symptomatic cases? That is collected in communities throughout the world. As it is collected continuously, it should serve to track those kind of cases over time, showing spread & growth. Those with symptoms wouldn't have been allowed to give blood. I presume temperature and BP are recorded for each blood donation.
As I understand it, the collected blood wouldn't have the virus itself, but should be appropriate for antibody tests.
Given this seems obvious, I wonder whether it is already in process for the Stanford antibody test. Or maybe it isn't as obvious as I think.
[BC already mentioned China testing blood in another thread, and finding a rather low percentage of cases there.]
By the way, I ran across info on the PCR test used by China in the appendix of this NEJM article.
RE: What is the denominator - BostonCard - 04-10-2020
Here's a paper arguing the denominator is much larger than we thought.
https://www.medrxiv.org/content/10.1101/2020.04.01.20050542v1
Short version, if you look at reports of "influenza like illness" but scale it for the proportion of tests that are positive, you find that there was a lot of unexplained illness out there, that might be mildly symptomatic Covid-19. According to the authors, just in the week starting on March 15, 2020 there may have been up to 10 million Covid-19 cases presenting as mild flu. If that's the case, the denominator is much larger than we thought and the CFR (as these are symptomatic patients) may be closer to 0.1% than 2%.
This Economist article summarizes the paper well:
https://www.economist.com/graphic-detail/2020/04/11/why-a-study-showing-that-covid-19-is-everywhere-is-good-news
BC
RE: What is the denominator - 2006alum - 04-10-2020
(04-10-2020, 12:45 AM)BostonCard Wrote: Here's a paper arguing the denominator is much larger than we thought.
https://www.medrxiv.org/content/10.1101/2020.04.01.20050542v1
Short version, if you look at reports of "influenza like illness" but scale it for the proportion of tests that are positive, you find that there was a lot of unexplained illness out there, that might be mildly symptomatic Covid-19. According to the authors, just in the week starting on March 15, 2020 there may have been up to 10 million Covid-19 cases presenting as mild flu. If that's the case, the denominator is much larger than we thought and the CFR (as these are symptomatic patients) may be closer to 0.1% than 2%.
This Economist article summarizes the paper well:
https://www.economist.com/graphic-detail/2020/04/11/why-a-study-showing-that-covid-19-is-everywhere-is-good-news
BC
To which I return to my earlier question: can anyone remember a leader of a modern developed nation being admitted to the ICU for the flu? Boris Johnson staked his reputation on COVID-19 being not that much worse than the flu, so he clearly had no political incentive to be admitted to the ICU. Yes, it's an anecdote. But there's no way to spin how devastating that anecdote is to anyone who thinks this is no different from the flu.
RE: What is the denominator - M T - 04-10-2020
My opinion is that people in one profession (that happens to make them well known) are not necessarily someone to trust about guidance in other fields.
Don't trust me for economic theories -- that's not my expertise. Be wary of politicians as doctors, actors as philosophers, athletes as lawyers, etc.
RE: What is the denominator - Goose - 04-10-2020
(04-10-2020, 07:30 AM)M T Wrote: My opinion is that people in one profession (that happens to make them well known) are not necessarily someone to trust about guidance in other fields.+1000. Totally agree. Unfortunately in today's society it often seems that such persons are the preferred choice. I would also add that I would not trust someone who is in the field that can't explain their position to your satisfaction. I think it was Einstein (anyway, someone like that) who said "If you can't explain complex Physics to a layman, perhaps you don't understand it well enough yourself."
RE: What is the denominator - Mick - 04-10-2020
(04-10-2020, 12:55 AM)2006alum Wrote: To which I return to my earlier question: can anyone remember a leader of a modern developed nation being admitted to the ICU for the flu? Boris Johnson staked his reputation on COVID-19 being not that much worse than the flu, so he clearly had no political incentive to be admitted to the ICU. Yes, it's an anecdote. But there's no way to spin how devastating that anecdote is to anyone who thinks this is no different from the flu.
I don't actually remember it, but President Wilson was hospitalized during the Spanish Flu.
https://www.whitehousehistory.org/spanish-influenza-in-the-presidents-neighborhood
RE: What is the denominator - 2006alum - 04-10-2020
Incidentally, the Hill just noted that just from Sunday-Wednesday of this week, more New Yorkers have died of COVID-19 (officially, 2,906) than died on 9/11. That got me wondering how many New Yorkers die of the flu in a given year: per the CDC, a total of 4,517 New Yorkers died of flu and pneumonia combined in 2017.
To which I will again ask: if New York is likely to have as many COVID-19 deaths in one week as it has in combined flu and pneumonia deaths in one year, how can anyone credibly argue this virus yields outcomes no worse than the flu?
RE: What is the denominator - Mick - 04-10-2020
(04-10-2020, 07:30 AM)M T Wrote: My opinion is that people in one profession (that happens to make them well known) are not necessarily someone to trust about guidance in other fields.
You could frame this for any profession. Sarcasm alert: Nothing gives me greater joy than to hear a lawyer talk to me about marketing/sales (my field for 30+ years). I wouldn't think of drafting a contract, why do they tell me how to do my job?
RE: What is the denominator - BostonCard - 04-10-2020
So, there are some issues with the serology tests (no surprise, no one claims they are perfect, but depending on their use, this could be problematic)
https://www.research.ox.ac.uk/Article/2020-04-05-trouble-in-testing-land
BC