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Right... lets keep focusing on PCR lab based medical testing for a public health war
A public health test with a:
-24 hour delay is just OK
-48 hour delay really losing its use
-72 hour delay almost irrelevant for transmission
-96 hour delay - waste https://www.cnbc.com/2020/11/18/covid-testing-faces-delays-again-as-demand-spikes-ahead-of-the-holidays-.html?__source=iosappshare%7Ccom.apple.UIKit.activity.PostToTwitter
A public health test with a:
-24 hour delay is just OK
-48 hour delay really losing its use
-72 hour delay almost irrelevant for transmission
-96 hour delay - waste https://www.cnbc.com/2020/11/18/covid-testing-faces-delays-again-as-demand-spikes-ahead-of-the-holidays-.html?__source=iosappshare%7Ccom.apple.UIKit.activity.PostToTwitter
2/ We have to recognize that the tools we need to fight this war are sitting right in front of us.
Blocked by a medical enterprise that can't see a forest, just trees
A government that fails to recognize the gravity of the situation we are in https://twitter.com/michaelmina_lab/status/1328873625894719489?s=20
Blocked by a medical enterprise that can't see a forest, just trees
A government that fails to recognize the gravity of the situation we are in https://twitter.com/michaelmina_lab/status/1328873625894719489?s=20
3/ Some people say rapid antigen testing is not good enough. "Some infected people might slip by!"
First: Essentially everyone is "slipping by" right now. People are either tested post-transmissible stage or getting results too late to act.
Most are just not getting tested!
First: Essentially everyone is "slipping by" right now. People are either tested post-transmissible stage or getting results too late to act.
Most are just not getting tested!
4/ But the biology is perhaps the most important piece. A rapid #COVID19 test is highly sensitive to detect people when they are most infectious. This is no longer in question.
It shouldn't have been months ago. We knew already.
It definitely is not now....
It shouldn't have been months ago. We knew already.
It definitely is not now....
5/ Some people say that the PCR test can detect you a day earlier than an antigen test and so the PCR test is better to find people early before they infect others...
This is faulty thinking. It's the WRONG comparison to make.
This is faulty thinking. It's the WRONG comparison to make.
6/ The RIGHT comparison is not the sensitivity of the rapid test against the sensitivity of PCR taken at the same time
The correct comparison is: what is the sensitivity of the rapid test at the time the PCR test is resulted....24-96 hours after the PCR swab is collected!
The correct comparison is: what is the sensitivity of the rapid test at the time the PCR test is resulted....24-96 hours after the PCR swab is collected!
7/ If you take PCR that is 48 hours to return and it detects low RNA early in infxn that the rapid test doesn't detect... Sounds not good for rapid test
BUT 24 hours later the viral load will grown 1,000,000x --> Ag test is Positive!
Yet PCR still not back yet!
...
BUT 24 hours later the viral load will grown 1,000,000x --> Ag test is Positive!
Yet PCR still not back yet!
...
8/ The POINT is when evaluating sensitivity of a lab PCR against a RAPID test, and worried about rapid test not detecting early infection - we MUST consider the speed/kinetics of the virus - it's why its a RAPID test!
This is why lab-MEDICINE is not same as public health testing
This is why lab-MEDICINE is not same as public health testing
9/ In Lab Medicine we compare two tests against the SAME specimen - b/c it's MEDICINE - and we assume we have "one shot"
In Public Health Testing we consider testing Regimens and Timing/kinetics at a population level. The considerations are VERY different.
In Public Health Testing we consider testing Regimens and Timing/kinetics at a population level. The considerations are VERY different.
10/10 This is why @US_FDA must make a new publichealth test evaluatory pathway that has the flexibility to consider testing situations that are distinct from clinical care.
Mixing them is muddying the expectations for a clinical test and blocking widescale public health tests.
Mixing them is muddying the expectations for a clinical test and blocking widescale public health tests.
We detail this here.... https://www.medrxiv.org/content/10.1101/2020.06.22.20136309v3
We also detail this here...
w/ @DanLarremore and Roy Parker https://www.nejm.org/doi/full/10.1056/NEJMp2025631
w/ @DanLarremore and Roy Parker https://www.nejm.org/doi/full/10.1056/NEJMp2025631
