Urgent @US_FDA @CDCgov #AndWhoeverWillListen

Rapid paper strip tests can be extremely powerful public health tools

But they cannot just be introduced without major information campaign AND clear algorithm for use - like the CDC HIV algorithm.

1/x

https://www.nytimes.com/live/2020/10/07/world/covid-coronavirus#nevada-halts-use-of-rapid-coronavirus-tests-in-nursing-homes-citing-inaccuracies

Despite high sensitivity when someone is likely contagious, and high specificity relatively speaking - 98%,

When deployed widely, a 2% false positive rate (1 per 50) is too high.

2/x

If deployed alone, a pop screening tests with a 1 in 50 false positive rate will immediately create a lack in confidence of the assay. This is already happening!

I’ve said it before - directly to FDA/CDC and here - we MUST have a clear goal and plan for these tests.

3/x

At the very least we MUST

1) make it known that false positives are normal and expected

2) provide opportunity to immediately use a confirmatory rapid test. This can drive false positives to 1 per 2000. An acceptable number

This is not a new problem in clinical medicine

4/x

In our Hospital, 50% of positive HIV screens are false positive. Do we say the screen is worthless and stop the program? Absolutely not. Instead we have and follow an algorithm.

If test 1 Positive, then do orthogonal second tests

If second test positive, presume positive

5/x

This is an age old problem of screening and what we have to do is explain the tests well and plan for this as a clear expected scenario and make confirmatory testing part of the process. Package a few confirmatory tests with the large group of initials screen RDTs

Moreso...

6/x

We simply need guidance and we need that guidance to be loud and clear and ideally should come from the federal level. Most ID clinicians know the CDC HIV algorithm. It is high time we create a similar algorithm for the use of Rapid tests, before we just essentially release them.