NOTE:

If you see papers/media that show very low sensitivity for rapid Ag tests (i.e. 30%-60% sensitivity) the report is most likely making a common mistake:

Comparing a test meant to detect viable virus to a test that can detect minuscule amounts of RNA is a mistake.

1/x

PCR RNA stays around long after live virus is cleared

So if you see a paper that shows very low sensitivity, ask:

"Are they comparing rapid antigen tests to "anytime" PCR RNA positivity? (Especially studies asking about sensitivity among asymptomatics)

2/x
To interpret this, you should know that only 25%-40% of the time someone is PCR positive are they infectious w live virus.

So... even a test that is 100% sensitive for live virus should only show a 25%-40% sensitivity against PCR among asymptomatic people.

3/x
(For various more epidemiologically complicated reasons having to do with the growth or decay rate of the epidemic, the sensitivity range is actually more like 30% - 60%... but that's for another tweet sometime)...

But to interpret studies of rapid antigen tests...
4/x
Simply put... If you see reports of rapid antigen tests "only" 30% - 60% sensitivity in asymptomatics (vs PCR) - you should think:

"Great! That could well be an exceptional test with sensitivity as high ~905-100% sensitive for likely contagious virus - and its rapid!"

5/x
This is too important to allow yourself to be misguided.

So, unfortunately here, don't always believe scientific papers

You have to ask "Why is the test being done?"

If it is to detect asymptomatic contagious people, then know that comparing vs. PCR is misleading.

6/6
Also, PLEASE don't look only at Ct values against Rapid Ag tests. Need a way to understand what each Ct represents. Some platforms run ~8 Cts lower than CDC / WHO assays. This means that every platform needs to be considered individually. Can Not just say "Ct < 30" = "live virus"
We are finding that whole platforms consistently run low. TaqPath it seems runs low for instance.

So in that case, a Ct of 23 may be more like a Ct of 29/30. This was the case in Liverpool and I believe recently a JCM paper looking at BinaxNOW among asymptomatics in Utah.
Also this: https://t.co/KgmLcvVlS5

More from Society

Two things can be true at once:
1. There is an issue with hostility some academics have faced on some issues
2. Another academic who himself uses threats of legal action to bully colleagues into silence is not a good faith champion of the free speech cause


I have kept quiet about Matthew's recent outpourings on here but as my estwhile co-author has now seen fit to portray me as an enabler of oppression I think I have a right to reply. So I will.

I consider Matthew to be a colleague and a friend, and we had a longstanding agreement not to engage in disputes on twitter. I disagree with much in the article @UOzkirimli wrote on his research in @openDemocracy but I strongly support his right to express such critical views

I therefore find it outrageous that Matthew saw fit to bully @openDemocracy with legal threats, seeking it seems to stifle criticism of his own work. Such behaviour is simply wrong, and completely inconsistent with an academic commitment to free speech.

I am not embroiling myself in the various other cases Matt lists because, unlike him, I think attention to the detail matters and I don't have time to research each of these cases in detail.

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