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Michael Mina Profile picture
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9 Jan, 4 tweets, 3 min read
Honestly @US_FDA @CDCgov

HOW have we FAILED to get frequent rapid testing out?!

•The science & plans are there

•All you've given is pushback

Almost 5 months ago I wrote:

"So we're not looking back 5 months from now wishing we acted"

PLEASE ACT NOW!

@ASMicrobiology @APHL
I know @ASMicrobiology & @APHL you do not support these tests - pity

Confounding sensitivity & specificity for EFFECTIVENESS in midst of a pandemic is a dangerous and now deadly decision

(1) Define the use
(2) Then take a stance on test effectiveness

You never really did (1)
Here is a primer for what I'm referring to.

And here is an expert letter signed by 50+ respected Scientists and Physicians in support of this as an additional mode of slowing spread.

rapidtests.org/expert-letter

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More from @michaelmina_lab

Michael Mina Profile picture
10 Jan
UK Rolling out #COVID19 Rapid Tests!

**NOTE: A quote says rapid tests missed 60% of positives in Liverpool

NOT accurate

VAST majority of MISSES were LOW PCR RNA & thus NO LONGER CONTAGIOUS.

(PCR remains Positive for a long time, rapid Ag does not)

theguardian.com/world/2021/jan…
Despite some poor messaging in UK - Rapid Ag tests work WELL to find CURRENTLY INFECTIOUS ppl

Frequent rapid Ag testing sensitivity is >95% to find infectious people.

(ppl get confused & say they're low sensitivity - but that's when compared to RNA on PCR from prior infection)
A major attribute of rapid Ag testing is they can be FREQUENT

It's not the sensitivity of a test to find virus particles that matters

It's the sensitivity of the testing program to find and isolate infectious people that matters.

For that, PCR often fails. Rapid Tests do well.
Read 6 tweets
Michael Mina Profile picture
8 Jan
#COVID19 is overlooked by the world as as urgent a crisis in Africa as every where else

We continue to make the same mistakes of confusing a lack of testing for a lack of cases.

In this study in Zambia, ~20% of deaths were found to be COVID related!

1/
medrxiv.org/content/10.110…
To determine this, the researchers performed a systematic analysis of swabbing and running PCR on post-mortem individuals.

These ppl would not have been detected/confirmed as having COVID otherwise and thus not officially reported owing to a lack of testing infrastructure

2/x
As @brookenichols has discussed, rapid Ag testing isnt only a powerful tool for frequent use to slow spread (as I’ve discussed) - it is also a powerful tool for less resourced countries to access and massively scale up testing to get formal estimates of transmission/cases

3/x
Read 6 tweets
Michael Mina Profile picture
4 Jan
Short THREAD.

On False POSITIVES of rapid antigen tests.

This 🧵 is on SPECIFICITY or the issues of False POSITIVES and rapid antigen tests.

Many people are concerned that these fast, inexpensive tests cause too many false positives and will overload PCR labs...

1/x
Rapid antigen tests can have 98%-99.9% specificity meaning between 0.1% and 2% of tests run might be falsely positive.

If prevalence is low, even a 99.9% specificity could mean many of the positive tests are falsely positive.

But w rapid tests, there are rapid solutions!

2/x
Many ppl instinctively worry that a false positive will mean an erroneous 10 day isolation and that huge numbers of people are going to require laboratory based PCR confirmation tests and this will overload the system.

No, this is stuck-in-our-ways thinking...

3/x
Read 14 tweets
Michael Mina Profile picture
4 Jan
@apoorva_nyc @TakeWeightOffMD Seen a lot of responses talking about partial immunity here.

But, Unlike antibiotics, the comparison has to consider even greater “only partial immunity” among those who have had no vaccine by the time they get infected.

1/x
@apoorva_nyc @TakeWeightOffMD The immune response is going to develop whether you’ve been vaccinated or not. If you’ve had no vaccine, then there is going to be much more “only partial immunity” that the virus gets to play around with and “test out”

2/x
@apoorva_nyc @TakeWeightOffMD We have to very careful to not forget what the baseline is here. W antibiotics, the Bacteria is only exposed to a partial dose if youre on antibiotics. With immunity, the virus is exposed to a partial dose whenever you’re not already protected while immunity builds up.

3/x
Read 6 tweets
Michael Mina Profile picture
4 Jan
THREAD **IMPORTANT** (IMO)

SO MUCH Continued CONFUSION about Rapid Antigen Tests - Now about Asymptomatics.

A New @CDC_gov @CDCMMWR study concludes Ag tests didn't work in Asymptomatic ppl. Simply put, It's wrong

Here I got in depth on Rapid Tests & how to evaluate them

1/x
The study found rapid Ag tests missed 40% of PCR +ve Asymptomatics.

BUT... FAILED to state that 100% of the misses were in ppl with NO CULTURABLE VIRUS (plus ALL had Ct values >30)

Rapid tests CAUGHT 100% of the infectious ppl!
cdc.gov/mmwr/volumes/6…

2/x
That's right!

In the very same study that concludes rapid Ag tests do not work in asymptomatic people, the authors failed to state the rapid Ag tests SUCCESSFULLY CAUGHT 100% of ASYMPTOMATIC PEOPLE who had likely contagious virus.

3/x
Read 31 tweets
Michael Mina Profile picture
3 Jan
Dear @CDCgov - Why can't you learn?

The paper concludes rapid Antigen tests had only 40% sensitivity in Asymptomatics

But failed to state they had 100% SENSITIVITY for what matters - culture +ve viable virus in Asymptomatics

PCR, not Ag, is wrong tool for Asymptomatic screens
The problem is simple

PCR remains +ve for long time after infectious

Meanwhile Ag tests are +ve only when infectious

If testing Asymptomatics randomly (vs. repeatedly) - they are MOST likely to be found post-infectious -> EXPECT Ag to be -ve MOST of time someone is PCR +ve
The very paper @CDCgov links to that concludes rapid Ag tests do not perform well in Asymptomatics literally shows 100% sensitivity for culture +ve samples in Asymptomatics

Massive failure to not emphasize this for asymptomatic screening.

cdc.gov/mmwr/volumes/6…
Read 6 tweets

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