Rapid antigen tests must catch virus on a paper strip
To catch virus, test manufacturers use ANTIBODIES (yes, antibodies like the ones in your immune system) to catch the virus
They make the antibodies and embed them, in a line, on the paper strip.
Thus a line forms if +ve
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Antibodies can come in all shapes and sizes (sort of)
Point is, some antibodies are much more specific and strong binders than others
Some are just... sticky. Some much more directed.
Some grab the virus more tightly - these may be used on the more sensitive rapid tests
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Moral of this little tutorial is... rapid antigen tests are not all created equal and they are generally only as good as the antibodies selected (usually discovered by sequencing an infected persons B cells) and printed on the paper....
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Some newer rapid antigen tests are a bit (or a lot) better than some that came out many months ago
For the newer ones, companies have simply had more time to sequence more people's B cells and dig deeper to find better, stronger, more specific antibodies for the test
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Lots of publications now have looked at the differences
So, If you're in a position to decide on a rapid testing program for your city, state or country - don't assume one test is same as the next. Simply put, and like everything in life, they simply aren't. :)
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First, the amazing efficacy from phase 3 at this point for both @moderna_tx and @pfizer vaccines - both mRNA vaccines - is EXCEEDINGLY ENCOURAGING.
These results show that these vaccines are eliciting the correct antibody bases responses to stop symptomatic infection!
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What I am worried about is the time scale of the trials thus far:
The leading vaccines are presenting the spike protein to the human immune system. This makes sense! Immunize against spike and stop virus entry into the cells.
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@elonmusk Great question! It’s more complex question and depends on why the test is being used - ie: do you want to know if you are currently contagious/risky to others or if you have any remnants of RNA? The difference may sound trivial but it is massive
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@elonmusk If the question is "Am I currently infectious right now when the swab is collected" then on *most* instruments/labs, data suggests a Ct value somewhere around 30 or below is needed. (Different instruments/labs are different - but that's a decent generalization)...
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@elonmusk If the question is "Am I becoming infectious" then even if you have a high Ct value... say 38... then it's important to test again the next day. If you go to 28, then you better stay put, you're likely infectious for the next 5-8 days or so...
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The paper 👆by one of the leading groups in the world on #COVID19 testing @c_drosten.
The paper supports precisely what we have shown in our research for these tests to be used as powerful public health screening tools to slow/stop outbreaks
The paper evaluates multiple antigen tests and finds a wide variety of specificities and analytical sensitivities
Drives home message that not all antigen tests are the same! These tests use antibodies to capture the virus and these will induce potentially major differences
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