FINALLY Americans are seeing the value of at-home rapid tests, and demanding them to help keep their families, friends, neighbors safe and schools and businesses running.
But now the US govt needs to make more highly accurate rapid tests available to meet that demand.
In many parts of world, rapid testing is commonplace. Policymakers recognized early that rapid tests could blunt the pandemic by scuttling transmission chains. They created special regulatory pathways to evaluate these tests, quickly & effectively
@nytopinion@nytimes@TheCOVIDCollab 4/
In the US, our already overburdened regulatory authorities have had an impossible task – evaluate a tool meant for public health as a medical device. Its clear that the US should follow in Europe’s footsteps & stand up a public health evaluation track to evaluate rapid tests.
@POTUS already gave his public health directive to the country – vaccinate or weekly testing
Now he should use executive power to designate rapid tests as the public health tools they are, to regulate them appropriately for their public health transmission stopping benefits
Frequent rapid testing especially in schools is one of the best ways to keep kids in schools. We can avoid unnecessary quarantines by using highly accurate rapid tests.
The highly contagious Delta variant makes knowing your Covid status in real- time more important than ever. We need to ensure that the U.S. has enough supply and that all Americans have free access to these powerful public health tools.
@nytopinion@nytimes@TheCOVIDCollab@POTUS 9/
And with new treatments and therapies coming out that must be started SOON after symptoms, we need to ensure people have both ready access to tests when they need them, and get fast results, from home
Especially rural US where lab testing far too slow
@nytopinion@nytimes@TheCOVIDCollab@POTUS 10/
Of course, thank you to the many public health experts who have advocated for rapid tests with us. Together we can change the system.
The path to increase access is charted.
Now it’s on USGov / president to make this happen.
It is almost universal that any piece discussing Rapid Ag tests says “PCR is more accurate but…”
But even this isn’t true. It simply depends what you want to detect.
If wanting to identify ppl who are contagious, PCR is much less accurate.
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If your goal is to detect ppl are infectious, a rapid Ag test is highly sensitive AND specific for this.
PCR is not specific for this. It will read positive even when not infectious. So… it’s less accurate for the public health question at hand “am I infectious”
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You might say… well PCR is much more sensitive. But even that is not true. A bit more, yes, but if wanting to catch infectious ppl, it’s really but that much more sensitive and, if that’s your goal, then PCR is massively LESS effective than a rapid test.
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A very important piece is the temporal relationship between when viral RNA is highest, when antigen tests are highest sensitivity and when people are most likely to be infectious following exposure. While almost no studies directly observe all three together...
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@MarkZlochin@CircusPubes@DrPathHero1 They all fall directly in line with the exact same time period after exposure or - when symptoms are demonstrated, with the same period surrounding onset of symptoms.
So we really do not need empirical data showing transmission and viral load since the kinetics show it all
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@MarkZlochin@CircusPubes@DrPathHero1 A major problem obtaining the direct empirical data is that if someone is testing, they likely aren't infecting others. So, people who are infecting others, you simply are not getting their swab at the same time as they are infecting. So relationships are skewed.
Luckily, the issue is a simple one to fix (all things considered).
The tests exist in HUGE numbers across the globe. Just not in the US. The reason? We've asked the FDA to take on an impossible task... to evaluate high quality PUBLIC HEALTH tools, when this is not their job
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The FDA evaluates medical devices - and does not evaluate public health tools
This is THE problem. As long as we consider rapid tests as medical devices (they're not - they're PUBLIC HEALTH transmission detection tools) FDA is forced to fit a square peg in a round hole
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Its common to say ALL kids mask during school, w out mention of daily rapid tests for entry
Yet, it’s heresy to suggest ALL kids test daily and go maskless
- Poor fitting Masks cut transmission, maybe <50%
- Rapid tests cut risk of infectious entering by >90%
I’m NOT suggesting we not do both. But dilemma is:
Why is it that when masks are discussed, rapid tests in AM are not. BUT when rapid tests in AM are discussed, it has to always be followed by “And masks too”.
Demonstrates group think rather than science backed decisions
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We DO need rapid test supply. Many ways to make it happen. Change of how they are designated (as a public health tool) is first step in my view so that we can massively accelerate access and scale
Rapid tests work very well to answer 🧵
AM I INFECTIOUS and a RISK TO OTHERS
This is THE public health ? we care about
I made a BIG chart of rapid tests
- Overall sensitivity vs any PCR pos - what FDA judges
- Sensitivity if infectious (97%!) - what we actually care about
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This data above comes from the UK COVID-19 Lateral Flow Oversight Team.
What the data above shows is that rapid tests are excellent public health tools to quickly identify almost anyone who is currently infectious and needs to isolate
What it also shows is...
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This shows why there is so much damn confusion about if rapid tests are sensitive
Answer: YES they are... if the question is "Am I Infectious Now and do I need to isolate"
However, if we compare them to PCR, then we are asking a different question: Do I have any RNA in me
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- Moderately infectious (ie infect 2 or 3 ppl in a classroom): 90-95%
- Mildly infectious (ie spread to spouse only) ~80-90%
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This Graph of viral load over time helps to explain this sensitivity issue:
Further, symptoms vs no symptoms has no impact on test performance. Studies that say it does are not recognizing the sampling bias that enters their studies.
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