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Asymptomatic Deep-Dive
Read on, you’ll be surprised
This NYT article revealed that high Ct PCR was identifying mostly non-infectious positives (trace viral RNA)
The upside to supersensitive PCR is that it also tells us a lot about asymptomatics
1 https://www.nytimes.com/2020/08/29/health/coronavirus-testing.html
Read on, you’ll be surprised
This NYT article revealed that high Ct PCR was identifying mostly non-infectious positives (trace viral RNA)
The upside to supersensitive PCR is that it also tells us a lot about asymptomatics
1 https://www.nytimes.com/2020/08/29/health/coronavirus-testing.html
First, the prisons
Case 1) Marion Correctional Institution: 95% asymptomatic of 2,028+
Case 2) In 4 state prison systems - Arkansas, North Carolina, Ohio and Virginia: 96% asymptomatics of 3,277+
2 https://www.reuters.com/article/us-health-coronavirus-prisons-testing-in-idUSKCN2270RX
Case 1) Marion Correctional Institution: 95% asymptomatic of 2,028+
Case 2) In 4 state prison systems - Arkansas, North Carolina, Ohio and Virginia: 96% asymptomatics of 3,277+
2 https://www.reuters.com/article/us-health-coronavirus-prisons-testing-in-idUSKCN2270RX
3) Neuse Correctional Institution: 98% asymptomatic of 444+
This below article is misleading
Yes, some were presymptomatic at time of testing, but they didn’t significantly change result
DRC: “disputed any notion that DRC is “walking back” its claim”
3 https://ohiocapitaljournal.com/2020/06/17/ohio-prisons-chief-walks-back-claim-that-96-of-prison-covid-19-cases-were-asymptomatic/
This below article is misleading
Yes, some were presymptomatic at time of testing, but they didn’t significantly change result
DRC: “disputed any notion that DRC is “walking back” its claim”
3 https://ohiocapitaljournal.com/2020/06/17/ohio-prisons-chief-walks-back-claim-that-96-of-prison-covid-19-cases-were-asymptomatic/
Case 4: Tyson Foods, Arkansas: 95% asymptomatic of 481+
“Of the 3,748 team members tested, 481 tested positive for COVID-19, and 455 were asymptomatic.”
4 https://katv.com/news/local/nearly-95-percent-of-tyson-foods-employees-with-covid-19-were-asymptomatic-company-says
“Of the 3,748 team members tested, 481 tested positive for COVID-19, and 455 were asymptomatic.”
4 https://katv.com/news/local/nearly-95-percent-of-tyson-foods-employees-with-covid-19-were-asymptomatic-company-says
Case 5: Tyson Foods, Missouri: 85% asymptomatic of 291+
Note - Ct means cycle threshold or how many cycles of PCR you run to amplify RNA. Low 30’s is normal and picks up normal infections. 40 is high and can amplify trace amounts of RNA
5 https://apnews.com/d3646ba688a79eba78db3bcabee80b24
Note - Ct means cycle threshold or how many cycles of PCR you run to amplify RNA. Low 30’s is normal and picks up normal infections. 40 is high and can amplify trace amounts of RNA
5 https://apnews.com/d3646ba688a79eba78db3bcabee80b24
Case 6: Tyson Food, North Carolina: Majority asymptomatic of 570+
“a majority of employees with coronavirus were asymptomatic and otherwise would not have been identified as having Covid-19 had they not been tested.”
6 https://edition.cnn.com/2020/05/22/business/tyson-plant-north-carolina-coronavirus-trnd/index.html
“a majority of employees with coronavirus were asymptomatic and otherwise would not have been identified as having Covid-19 had they not been tested.”
6 https://edition.cnn.com/2020/05/22/business/tyson-plant-north-carolina-coronavirus-trnd/index.html
Case 7: Pacific Seafood, Oregon: 95% asymptomatic of 124+
“The company said 95 percent of those who tested positive did not report any symptoms. None have been hospitalized.”
7 https://www.oregonlive.com/coronavirus/2020/06/65-coronavirus-cases-reported-at-pacific-seafood-facility-in-newport.html
“The company said 95 percent of those who tested positive did not report any symptoms. None have been hospitalized.”
7 https://www.oregonlive.com/coronavirus/2020/06/65-coronavirus-cases-reported-at-pacific-seafood-facility-in-newport.html
Case 8: Meat Processing Plants: 9,000+ employees across the plants were mass tested -> 1/3 PCR+ -> 95% Asymptomatic
Source: Direct contact with top management
8
Source: Direct contact with top management
8
Case 9: Triumph Foods, Missouri: 100% asymptomatic of 373+
9 https://edition.cnn.com/2020/05/04/us/triumph-foods-outbreak-missouri/index.html?utm_medium=social&utm_content=2020-05-04T09%3A01%3A02&utm_source=twCNN&utm_term=link
9 https://edition.cnn.com/2020/05/04/us/triumph-foods-outbreak-missouri/index.html?utm_medium=social&utm_content=2020-05-04T09%3A01%3A02&utm_source=twCNN&utm_term=link
Case 10: Karachi, Pakistan:
“Aga Khan University's researchers have discovered in a study that 95% of those who had tested positive for Covid-19 through blood tests, which register the presence of antibodies to fight the disease, were asymptomatic.”
10 https://tribune.com.pk/story/2262980/1
“Aga Khan University's researchers have discovered in a study that 95% of those who had tested positive for Covid-19 through blood tests, which register the presence of antibodies to fight the disease, were asymptomatic.”
10 https://tribune.com.pk/story/2262980/1
Case 11: Bao, India: 95% asymptomatic
“Health Department statistics show that 95 per cent of the patients in Goa, who have tested positive for Covid-19 are asymptomatic”
11 https://www.indiatvnews.com/news/india/95-per-cent-of-covid-19-patients-in-goa-are-asymptomatic-official-624416
“Health Department statistics show that 95 per cent of the patients in Goa, who have tested positive for Covid-19 are asymptomatic”
11 https://www.indiatvnews.com/news/india/95-per-cent-of-covid-19-patients-in-goa-are-asymptomatic-official-624416
Case 12: Maharashtra, India: 97% asymptomatic or mild
“Maharashtra recorded 150,658 active Covid-19 cases till Sunday afternoon, of which 97% are either asymptomatic or mildly symptomatic.”
12 https://www.hindustantimes.com/mumbai-news/97-covid-positive-patients-are-asymptomatic-or-mildly-symptomatic/story-oNgUvQXCU7fRUPVC3yI9mM.html
“Maharashtra recorded 150,658 active Covid-19 cases till Sunday afternoon, of which 97% are either asymptomatic or mildly symptomatic.”
12 https://www.hindustantimes.com/mumbai-news/97-covid-positive-patients-are-asymptomatic-or-mildly-symptomatic/story-oNgUvQXCU7fRUPVC3yI9mM.html
These aren’t scientific studies so they have limitations
Also need to factor in ages, health, who is tested
But this official survery of care homes in the UK shows that:
“80.9% of residents who tested positive were asymptomatic (5,455 out of 6,747)”
13 https://www.gov.uk/government/publications/vivaldi-1-coronavirus-covid-19-care-homes-study-report/vivaldi-1-covid-19-care-homes-study-report
Also need to factor in ages, health, who is tested
But this official survery of care homes in the UK shows that:
“80.9% of residents who tested positive were asymptomatic (5,455 out of 6,747)”
13 https://www.gov.uk/government/publications/vivaldi-1-coronavirus-covid-19-care-homes-study-report/vivaldi-1-covid-19-care-homes-study-report
There are also studies/reports that show that asymptomatics are far lowerer
Yes, but there are two major confounders which come into play with this type of study
WAPO article:
https://www.washingtonpost.com/health/2020/08/08/asymptomatic-coronavirus-covid/
14
Yes, but there are two major confounders which come into play with this type of study
WAPO article:
https://www.washingtonpost.com/health/2020/08/08/asymptomatic-coronavirus-covid/
14
Confounders:
1. AB testing misses many asymptomatics who serorevert quite fast
2. Ct count for PCR - the more cycles, the more likely you are to pick up trace RNA from low level imfections (asymps). Lower Ct would pick up far fewer
Methodology also important - who u testing?
15
1. AB testing misses many asymptomatics who serorevert quite fast
2. Ct count for PCR - the more cycles, the more likely you are to pick up trace RNA from low level imfections (asymps). Lower Ct would pick up far fewer
Methodology also important - who u testing?
15
Some of these studies are quite old and when I first saw them I could not make sense of them
When enough stuff wasn’t making sense I then realized that maybe the testing is letting us down
AB studies greatly underestimate number of infected/recovered
Moment of awakening:
16 https://twitter.com/gummibear737/status/1297495211308965888
When enough stuff wasn’t making sense I then realized that maybe the testing is letting us down
AB studies greatly underestimate number of infected/recovered
Moment of awakening:
16 https://twitter.com/gummibear737/status/1297495211308965888
So seroprevalence is mostly a fail, although if you notice in tweet 10 (Karachi), they found 95% asymps with AB testing - must have been recent infections
High cycle PCR on the other hand is able to amplify trace amounts of RNA and detect previous infections
17
High cycle PCR on the other hand is able to amplify trace amounts of RNA and detect previous infections
17
CDC still estimates asymptomatics at 35% because they are going by AB testing studies
Mass testing with high Ct PCR shows that they are much larger
So much larger that it changes the denominator for calculating IFR
18
Mass testing with high Ct PCR shows that they are much larger
So much larger that it changes the denominator for calculating IFR
18
In SIR modeling used to predict epidemiological evolution, R stands for recovered
This type of model can help calculate herd immunity
But for some reason, everybody is using seroprevalence as the correct measure of recovered
I disagree -> an asymptomatic is recovered
19
This type of model can help calculate herd immunity
But for some reason, everybody is using seroprevalence as the correct measure of recovered
I disagree -> an asymptomatic is recovered
19
In fact, to me the high numbers of asymptomatics is how we know that pre-existing immunity is real
How else could we explain so many people brushing off infection with the “novel” coronavirus
For most people, it’s just another coronavirus...no big deal
20
How else could we explain so many people brushing off infection with the “novel” coronavirus
For most people, it’s just another coronavirus...no big deal
20
So ultimately, it’s all about trying to identify an accurate denominator
If we know how many have been infected, we can accurately calculate IFR
We can also do a better job at identifying herd immunity
People say NYC can’t be at herd immunity with only 20% seroprevalence
21
If we know how many have been infected, we can accurately calculate IFR
We can also do a better job at identifying herd immunity
People say NYC can’t be at herd immunity with only 20% seroprevalence
21
Unlike some EU countries which are able to find new cases (although most are asymp), NY can’t
They are testing like crazy...can’t find cases
1% = false positive threshold
Maybe a stable 20% seroprevalence is indicative of a much higher number of recovered?
See this thread
22 https://twitter.com/gummibear737/status/1305967263405821954
They are testing like crazy...can’t find cases
1% = false positive threshold
Maybe a stable 20% seroprevalence is indicative of a much higher number of recovered?
See this thread
22 https://twitter.com/gummibear737/status/1305967263405821954
I think the data on asymptomatics sheds an important light on Covid-19
-Not nearly as deadly as thought
-Significant pre-existing immunity
-We are much closer to herd immunity than anybody thinks
-Lockdowns needlessly put vulnerables at risk (protect vulnerable only solution)
23
-Not nearly as deadly as thought
-Significant pre-existing immunity
-We are much closer to herd immunity than anybody thinks
-Lockdowns needlessly put vulnerables at risk (protect vulnerable only solution)
23
If this deep dive was easy for you to understand, then have a look at this deep dive into estimating NYC’s real number of recovered
24 https://twitter.com/gummibear737/status/1305215126379917314
24 https://twitter.com/gummibear737/status/1305215126379917314
That’s it
Sorry it was so long
If you learned something useful please RT first tweet in this thread
Keep Calm and Carry On
Sorry it was so long
If you learned something useful please RT first tweet in this thread
Keep Calm and Carry On
