Have been continually updating how to convey the idea of pushing for cheap $1 daily “low sensitivity” tests.

The “low sensitivity” word makes many people a bit queasy. And without an understanding of the biology and current tests, this is understandable.

1/n

Every measure of sensitivity needs a target. Missing the target is a false negative. Currently, the target that FDA expects new tests to hit is PCR positivity.

For daily rapid tests, we don’t actually want “low overall sensitivity”. That is not the primary goal.

2/n

Instead what we need to do is to change the target to something more meaningful than simply PCR positivity.

So Instead of saying we want low sensitivity compared to PCR (PCR detects Virus RNA even long after cases have resolved)...

3/

what I actually mean is we want cheap $1 fast daily tests to have high sensitivity to detect cases that are transmitting.

4/n

If cases with high (transmissible) viral loads become the target, then it’s not a push to achieve cheap $1 daily low sensitivity-to-detect-PCR-positive tests. It’s a push to achieve cheap $1 fast daily *HIGH sensitivity-to-detect-transmitting cases in time to act*

5/n

And to do that, the tests with high sensitivity-to-detect-infectious-people need to be more widespread, need to be used every day or two where outbreaks are occurring, and need only to detect greater than 100,000 or a million virus copies per ml - not 100 copies, like PCR.

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