Read on Twitter
Quick analysis of 10/10 Note from Dr. Conley:
- He says that Trump has met CDC criteria to be out of isolation. This is false
/1 https://twitter.com/tamarakeithnpr/status/1315096441120059393
- He says that Trump has met CDC criteria to be out of isolation. This is false
/1 https://twitter.com/tamarakeithnpr/status/1315096441120059393
Trump meets the criteria as someone who warrants 20 days of isolation.
The specific language is found on the CDC’s website: https://www.cdc.gov/coronavirus/2019-ncov/hcp/duration-isolation.html
/2
The specific language is found on the CDC’s website: https://www.cdc.gov/coronavirus/2019-ncov/hcp/duration-isolation.html
/2
Conley says that “this morning’s PCR sample demonstrates” that “he is no longer considered a transmission risk to others.”
This is an exceptional piece of jargon that could mean so many things, that it really means nothing at all.
/3
This is an exceptional piece of jargon that could mean so many things, that it really means nothing at all.
/3
We are led to believe that the PCR test that was used is able to measure the amount of virus in the sample, but that doesn’t square with what we know about persons with severe disease, namely that they continue to shed live virus for longer than those w/ mild disease…
/4
/4
Even if he weren’t, the studies cited by the CDC suggest that we should expect to see him shedding viral *fragments* —
The fact that there’s no clear readout of the testing parameters throws the entire statement into question…unnecessarily.
/5
The fact that there’s no clear readout of the testing parameters throws the entire statement into question…unnecessarily.
/5
As mentioned by @Adrian_H, I too, would be be inclined to believe that Trump is shedding viral fragments — but I need to see the raw data to reach the conclusion.
/6 https://twitter.com/adrian_h/status/1315100017724657665
/6 https://twitter.com/adrian_h/status/1315100017724657665
Conley goes on to mention “the assortment of advanced diagnostic tests obtained” to reinforce the point that there is no longer evidence of “actively replicating virus”
- There are multiple ways to interpret the statement, but we are not given enough info to figure it out
/7
- There are multiple ways to interpret the statement, but we are not given enough info to figure it out
/7
One way to evaluate potential infectivity is to literally expose cells to samples of the virus obtained from Trump —> then check to see if the cells have been infected by the virus
The WHO suggests that this approach may not be as sensitive as PCR: https://www.who.int/news-room/commentaries/detail/criteria-for-releasing-covid-19-patients-from-isolation
/8
The WHO suggests that this approach may not be as sensitive as PCR: https://www.who.int/news-room/commentaries/detail/criteria-for-releasing-covid-19-patients-from-isolation
/8
Again, the wording doesn’t make it clear what is meant by “advanced diagnostic tests” so I suppose viral culture could still be a possibility.
If so, newer research does offer some support for its use, but in a roundabout way: https://jcm.asm.org/content/58/8/e01068-20
If so, newer research does offer some support for its use, but in a roundabout way: https://jcm.asm.org/content/58/8/e01068-20
Circling back to the more likely interpretation: the used a *quantitative* PCR test to measure the amount of active virus found in Trump’s sample(s).
The research behind this approach is well-established, and relies on an accurate calibration of the equipment
/10
The research behind this approach is well-established, and relies on an accurate calibration of the equipment
/10
This is where the cycle time (Ct) comes into play.
*Gross* simplification: think of PCR like a copy (Xerox) machine:
amount of *active* virus in the sample = the amount of toner in the machine
the cycle time = the number of copies you want to make
/11
*Gross* simplification: think of PCR like a copy (Xerox) machine:
amount of *active* virus in the sample = the amount of toner in the machinethe cycle time = the number of copies you want to make/11
Using this (grossly oversimplified) metaphor:
having enough toner to make all of your copies = having enough *active* virus in the sample to infect another person
if the copies become faded = there’s not enough live virus
/12
having enough toner to make all of your copies = having enough *active* virus in the sample to infect another personif the copies become faded = there’s not enough live virus/12
Before I get snarky comments: I’m aware that this metaphor is neither entirely accurate, and a gross simplification…but it’s helpful to set up the following point:
This assumes the use of a specific kind of PCR test
That assumption needs to be validated…
/13
This assumes the use of a specific kind of PCR testThat assumption needs to be validated…/13
We need Conley to clarify what he means because, even if we assume he was talking about this specific type of PCR:
Not all FDA authorized PCR tests on the market *can be used in this way*
There is no universal value for Cycle time
ref: https://www.medrxiv.org/content/10.1101/2020.08.04.20167932v4.full.pdf
/14
Not all FDA authorized PCR tests on the market *can be used in this way*There is no universal value for Cycle timeref: https://www.medrxiv.org/content/10.1101/2020.08.04.20167932v4.full.pdf
/14
Simply put, Dr. Conley is not giving us enough information to:
A) Know what he’s talking about, OR
B) Feel confident that he knows what he’s talking about, OR
C) Give him the benefit of the doubt.
/15
A) Know what he’s talking about, OR
B) Feel confident that he knows what he’s talking about, OR
C) Give him the benefit of the doubt.
/15
To his credit: Conley does mention “cycle threshold times" in this note, but does so in a way that reads more like they were using it for the *viral culture* approach I mentioned earlier.
So, again, it’s not clear what he’s referring to — and he appears to blend concepts.
/16
So, again, it’s not clear what he’s referring to — and he appears to blend concepts.
/16
Conley also mentions “undetectable subgeneric mRNA” — that's jargon for fragements of the virus that are unable to replicate
/17
/17
Circling back to note that Conley suggests that Trump had a fever sometime in the last 24-72 hours:
this note says Trump is “fever free for well over 24 hours”
the note from 10/7 noted 4-days without fever
the note from 10/8 did not report a temperature at all
/18
this note says Trump is “fever free for well over 24 hours”the note from 10/7 noted 4-days without feverthe note from 10/8 did not report a temperature at all/18
Final thoughts:
- More questions than answers
- Still don’t know:
— when Trump last tested negative
— what drugs or treatments he’s on
— imaging results
- Sounds like Trump had a fever recently
- Based on what we know, Trump should remain in isolation for another 10 days
/end
- More questions than answers
- Still don’t know:
— when Trump last tested negative
— what drugs or treatments he’s on
— imaging results
- Sounds like Trump had a fever recently
- Based on what we know, Trump should remain in isolation for another 10 days
/end
