Read on Twitter
1/17
It's been 2 weeks now since NYT reported up to 90% false positive due to "cycle threshold settings".
PCR cycle threshold topic is cruical.
As tweets usually have just a half-time of max. 30 min
Thread 
https://twitter.com/kerpen/status/1302234131707944961?s=20
It's been 2 weeks now since NYT reported up to 90% false positive due to "cycle threshold settings".
PCR cycle threshold topic is cruical.
As tweets usually have just a half-time of max. 30 min
Thread https://twitter.com/kerpen/status/1302234131707944961?s=20
2/17
As the NYT article is behind a paywall
here is all you need to know https://twitter.com/apoorva_nyc/status/1299705092178956288?s=19
As the NYT article is behind a paywall
here is all you need to know https://twitter.com/apoorva_nyc/status/1299705092178956288?s=19
3/17
"If you have to go more than 40 cycles to amplify a single-copy gene, there is something seriously wrong with your PCR“"
Source:
Michael A. Innis et al. PCR Protocols. A Guide to Methods and Applications, Academic Press, 1990.
"If you have to go more than 40 cycles to amplify a single-copy gene, there is something seriously wrong with your PCR“"
Source:
Michael A. Innis et al. PCR Protocols. A Guide to Methods and Applications, Academic Press, 1990.
4/17
German Tagesschau
"But many laboratories that evaluate the PCR tests do not stop the analysis at a Ct value of 30, but usually only at 37 or 40, as Uwe Dittmer explains." https://www.tagesschau.de/investigativ/ndr-wdr/gesundheitsaemter-corona-tests-101.html
German Tagesschau
"But many laboratories that evaluate the PCR tests do not stop the analysis at a Ct value of 30, but usually only at 37 or 40, as Uwe Dittmer explains." https://www.tagesschau.de/investigativ/ndr-wdr/gesundheitsaemter-corona-tests-101.html
5/17
Diagnostic detection of 2019-nCoV by real-time RT-PCR (Berlin, January)
"All oligonucleotides
were synthesised and provided by Tib-Molbiol, Berlin. Thermal cycling ...
and then 45 cycles "
Source WHO:
https://www.who.int/docs/default-source/coronaviruse/protocol-v2-1.pdf
Diagnostic detection of 2019-nCoV by real-time RT-PCR (Berlin, January)
"All oligonucleotides
were synthesised and provided by Tib-Molbiol, Berlin. Thermal cycling ...
and then 45 cycles "
Source WHO:
https://www.who.int/docs/default-source/coronaviruse/protocol-v2-1.pdf
6/17
May, refered study late Apri:
"... with Ct above 33 to 34 are not contagious and can be discharged from hospital care or strict confinement, according to a brief report published in the European Journal of Clinical Microbiology & Infectious Diseases" https://www.infectiousdiseaseadvisor.com/home/topics/covid19/ct-value-may-inform-when-patients-with-covid-19-can-be-safely-discharged/
May, refered study late Apri:
"... with Ct above 33 to 34 are not contagious and can be discharged from hospital care or strict confinement, according to a brief report published in the European Journal of Clinical Microbiology & Infectious Diseases" https://www.infectiousdiseaseadvisor.com/home/topics/covid19/ct-value-may-inform-when-patients-with-covid-19-can-be-safely-discharged/
7/17
@carlheneghan and Tom Jefferson
"Infectivity (defined as growth in cell culture) was significantly reduced when RT-PCR Ct values were over 24."
August 12, 2020
https://www.cebm.net/study/covid-19-clinical-utility-of-cycle-threshold-values/
@carlheneghan and Tom Jefferson
"Infectivity (defined as growth in cell culture) was significantly reduced when RT-PCR Ct values were over 24."
August 12, 2020
https://www.cebm.net/study/covid-19-clinical-utility-of-cycle-threshold-values/
8/17
Carl Heneghan recently recommended cut off 30
https://twitter.com/carlheneghan/status/1303220734689501184?s=20
Carl Heneghan recently recommended cut off 30
https://twitter.com/carlheneghan/status/1303220734689501184?s=20
9/17
PCR Test supplier are recommending 40 or "any signal positive"
Source: https://www.finddx.org/wp-content/uploads/2020/07/FIND_SARS-COV2_molecular-assay-evaluation-results_03Jul2020.pdf
https://twitter.com/pdubdev/status/1304286520853946369?s=20
PCR Test supplier are recommending 40 or "any signal positive"
Source: https://www.finddx.org/wp-content/uploads/2020/07/FIND_SARS-COV2_molecular-assay-evaluation-results_03Jul2020.pdf
https://twitter.com/pdubdev/status/1304286520853946369?s=20
10/17
Should guidelines be evidence-based? https://twitter.com/abirballan/status/1303924976932794368?s=20
Should guidelines be evidence-based? https://twitter.com/abirballan/status/1303924976932794368?s=20
11/17
"Number of cycles needed to achieve a positive related to outcome. Any positive that required more than 30 cycles should be questioned without good corroberative evidence."
https://twitter.com/ClareCraigPath/status/1303314465685987328?s=20
"Number of cycles needed to achieve a positive related to outcome. Any positive that required more than 30 cycles should be questioned without good corroberative evidence."
https://twitter.com/ClareCraigPath/status/1303314465685987328?s=20
12/17
Uruguay has developed an own PCR test and uses Ct cut off 35
https://twitter.com/FrankfurtZack/status/1303784617003151361?s=20
Uruguay has developed an own PCR test and uses Ct cut off 35
https://twitter.com/FrankfurtZack/status/1303784617003151361?s=20
13/17
Same in Taiwan, Ct cut off 35.
"Only samples with a CT value under 35 are considered positive in Taiwan, while those over 32 are unlikely to be contagious, Chuang said."
Source
https://focustaiwan.tw/society/202006250010
Same in Taiwan, Ct cut off 35.
"Only samples with a CT value under 35 are considered positive in Taiwan, while those over 32 are unlikely to be contagious, Chuang said."
Source
https://focustaiwan.tw/society/202006250010
14/17
CT > 35 contamination issues? https://twitter.com/Mirza_Muddassar/status/1299784122081124355?s=20
CT > 35
contamination issues? https://twitter.com/Mirza_Muddassar/status/1299784122081124355?s=20
16/17
Conclusion? https://twitter.com/EthicalSkeptic/status/1304250461164314626?s=20
Conclusion? https://twitter.com/EthicalSkeptic/status/1304250461164314626?s=20
17/17
Covid data is nosy, that's well known, isn't it? Main reason cycle threshold too high?
More than 50 "data errors" https://twitter.com/DaFeid/status/1284919954643591168?s=20
Covid data is nosy, that's well known, isn't it? Main reason cycle threshold too high?
More than 50 "data errors"
https://twitter.com/DaFeid/status/1284919954643591168?s=20
@kerpen
@FatEmperor
@boriquagato
@gummibear737
@EthicalSkeptic
@FrankfurtZack
@abirballan
FYI.
Collecting a few threshold items
@FatEmperor
@boriquagato
@gummibear737
@EthicalSkeptic
@FrankfurtZack
@abirballan
FYI.
Collecting a few threshold items
