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Below is a very bad article on Covid testing. It has poor thinking by *MDs* about testing.
And yes I, someone who is not a medical doctor, am claiming that medical doctors misunderstand how to evaluate Covid testing.
Cc: @michaelmina_lab @RapidTests http://nytimes.com/2020/12/01/health/coronavirus-testing-children.html
And yes I, someone who is not a medical doctor, am claiming that medical doctors misunderstand how to evaluate Covid testing.
Cc: @michaelmina_lab @RapidTests http://nytimes.com/2020/12/01/health/coronavirus-testing-children.html
Here's the problem, and it's really simple:
What needs to be evaluated is not a test.
The *testing system* is what needs to be evaluated.
Any journalist or MD talking about Covid testing that does not lead with this distinction is making a mistake.
What needs to be evaluated is not a test.
The *testing system* is what needs to be evaluated.
Any journalist or MD talking about Covid testing that does not lead with this distinction is making a mistake.
PCR-only testing systems are failing us. People cannot get tested. People often cannot get tested, and when they do are waiting up to many days for results.
Consequently, contagious people who got tested unknowingly spread the disease. https://www.nbcboston.com/news/local/calls-mount-for-more-coronavirus-testing-in-mass/2239901/
Consequently, contagious people who got tested unknowingly spread the disease. https://www.nbcboston.com/news/local/calls-mount-for-more-coronavirus-testing-in-mass/2239901/
My wife waited 3 days to get a test within 20 minute drive from our house. She waited another 3 days for results.
We waited *4 days* for my daughter's results.
This is now the norm. It is not the exception. https://www.boston25news.com/news/health/covid-19-test-turnaround-times-stretch-past-week-some/WHXMV4QXB5DN5PJYEVLFULXACI/
We waited *4 days* for my daughter's results.
This is now the norm. It is not the exception. https://www.boston25news.com/news/health/covid-19-test-turnaround-times-stretch-past-week-some/WHXMV4QXB5DN5PJYEVLFULXACI/
People don't quarantine after being tested to wait for results! Contagious people, like everyone, get tested, go about their daily lives as normal, and will only change their behavior after getting their results.
We need nearly immediate results to stop the spread.
We need nearly immediate results to stop the spread.
So: Not only do we need more testing. We also need as much testing as possible that delivers nearly immediate results.
In the absence of that, we have a broken testing system - one that cannot possibly help us control the pandemic.
In the absence of that, we have a broken testing system - one that cannot possibly help us control the pandemic.
This is why a PCR-based testing system no longer works. People cannot get tested in a timely fashion and they cannot get their results in time. So the pandemic spreads out of control.
In short: PCR tests are a very bad test around which to build a mass testing system.
In short: PCR tests are a very bad test around which to build a mass testing system.
What w should do is build a testing system as much as possible around rapid tests: from the Abbott ID to the Quidel Sofia to the Binax NOW and so on.
We need to massively augment our testing system with rapid so that people can get tested easily, and get results quickly.
We need to massively augment our testing system with rapid so that people can get tested easily, and get results quickly.
We should still use PCR for confirmatory, diagnostic, & pooled testing. We should still use PCR at institutions that can manage high throughput for a narrow population (as my university, Northeastern does).
But a *mass* testing system built around rapid tests works much better.
But a *mass* testing system built around rapid tests works much better.
Eg, In this episode of TWiV, @DanielGriffinMD talks about how people were tested using rapid tests. These people got results in 15 minutes or so. If they were positive, they could avoid interacting with others, thereby preventing the spread of the disease. https://www.microbe.tv/twiv/twiv-689/
This should be the norm everywhere.
But what about false negatives?!
This question must be retired. It is a meaningless question. It really needs to go. I wish all the MPH's & epis out there refused to answer it. Why?
Because what matters is the testing system not the test.
But what about false negatives?!
This question must be retired. It is a meaningless question. It really needs to go. I wish all the MPH's & epis out there refused to answer it. Why?
Because what matters is the testing system not the test.
To explain. The relevant comparison is not PCR sensitivity v. rapid test sensitivity.
It is between the probability of getting a PCR test, the turnaround time, & the sensitivity of that test vs. the prob. of getting a rapid test, the turnaround time, and the RAT sensitivity.
It is between the probability of getting a PCR test, the turnaround time, & the sensitivity of that test vs. the prob. of getting a rapid test, the turnaround time, and the RAT sensitivity.
I'm not sure how to model that ( @Ted4P some help here?).
But, if someone is 3 times more likely to get a rapid test w/ immediate results than getting a PCR test w/ results in 3 days, a lower sensitivity rapid test may be far, far better than a PCR test.
But, if someone is 3 times more likely to get a rapid test w/ immediate results than getting a PCR test w/ results in 3 days, a lower sensitivity rapid test may be far, far better than a PCR test.
At the very least, there should be no more NY Times articles, no more MDs, no more anyone with authority publicly disparaging a testing system that includes rapid antigen tests unless they can show that such a system is worse than the existing alternative.
Do not compare tests.
Compare testing systems.
the end
Compare testing systems.
the end
