At what point was the message of risk reduction (not elimination) and need for serial testing if we want to catch ppl when infectious lost.

There’s a weird focus on first day of infectiousness - as though all tests are day 1

1:

@EmilyAnthes

nytimes.com/2022/01/05/hea…
Importantly, this NYT article didn’t highlight the right interpretation of that study IMO. The majority of difference isnt PCR vs antigen.

The difference was Saliva vs Nasal swab.

When comparing PCR vs Antigen in nasal swab vs nasal swab, the relationship was as expected

2/
The title of the paper should have been

Discordant results between Saliva and Nasal swab specimens

But we’ve actually seen or known this for other variants - saliva becomes positive sooner

3/
Overall, the study adds to data we’ve seen for other variants & shows it MAY be exacerbated w Omicron

But it does NOT show reduced sensitivity of a rapid antigen test.

It shows increased transmissibility when the virus isn’t yet in nose.
totally different

4/

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More from @michaelmina_lab

5 Jan
THREAD:

This is an important study - supports anecdotes and other work by @awyllie13

Virus growing and detectable in saliva days earlier than the nose!

Both PCR & Ag in nose lag saliva 1-3 days

In Nose, PCR is 1 day faster than Ag (As Expected)

1/

medrxiv.org/content/10.110…
@awyllie13 Numerous reports show saliva comes up earlier and w Omicron there have been MANY anecdotes that throat swabs (which interact with saliva!) are turning positive BEFORE nasal swabs

And this pre-print suggests people are infectious when saliva turns positive

2/
Importantly, people are becoming symptomatic really fast too! As this study suggests

So we can use this to our GREAT advantage...

If beginning to feel Symptomatic - ASSUME positive, ASSUME infectious

w/ limited tests, hold on testing!

3/

Read 9 tweets
5 Jan
This thread by is going around
The numbers are not correct

We do not care about sensitivity against PCR -> We care about Sens against culturable/infectious virus

For that, rapid antigen tests are >90%

And the % infectious at day 5 used is inaccurate.

Its a nonsensical 🧵
Here’s an ex of why we can’t just use FDA numbers vs PCR

If we only compare vs PCR, you get poor sensitivity (here: ~400/800 or ~50%).

But if you compare viral loads that matter (culture pos), you get very high sensitivity: 93% here.

From medrxiv.org/content/10.110…
This is most commonly seen in asymptomatics. Why?

Because if asymptomatic - don’t have a clue if you’re PCR swab is taken when you are shedding live virus or Post infectious

So your just comparing Ag against anytime PCR positivity, regardless of if infectious.

3/
Read 4 tweets
4 Jan
Should @CDCgov reconsider guidance on isolation & add a Neg test? Yes!

Why?

Bc relationship between symptom start & peak virus load has changed!

Guidance must keep up accordingly.

To explain: I made a (tough to read) chart based on real experience of Prof. Kato @neurotheory
@CDCgov @neurotheory Here is the original tweet by @neurotheory showing this TERRIFIC Time course of tests.

@CDCgov @neurotheory I've written a bit more about this in a similar thread on Omicron, testing and symptoms.

3/

Read 7 tweets
3 Jan
Its finally dawning on me that there is an endless supply of ppl - many in public health & medicine - who will not understand science of testing & how to interpret the sea of (poorly performed) studies (including by CDC)

This is a failure of messaging by Federal government

1/
Confusion around rapid tests is becoming immensely harmful at local levels as every small town and city has their own decision makers trying to wade through a mix of confusing and often conflicting messages, with no guidance and no idea who or what to trust.

2/
The frustrating thing is that this doesn’t need to be hard!

The science and biology of rapid Ag tests is extremely simple/straightforward if we allow their formal evaluation to be towards why we take the tests: answering “Am I infectious” or “Do I need to isolate still?”

3/
Read 4 tweets
2 Jan
Uncomfortable Fact:

PCR stays Pos far too long

Most who test Pos on PCR are No Longer contagious-Esp if no symptoms

Millions have Isolated entirely AFTER contagious

(Rapid tests don’t cause this)

Why won’t FDA evaluate tests for how ppl use them: to answer “Am I Infectious?
PCR has its place…

For medical diagnostics OR when you know that someone was recently exposed etc

But 2 years in, we continue to use a Binary PCR to tell people they need to isolate, without using the right cutoff or tests to ask the public health question: am I infectious?
2/
Currently, FDA evaluate tests ONLY based on their medical diagnostic utility

2 years in to the worst public health crisis in modern history, there STILL is NO effort at FDA to regulate tests based on their ability to answer relevant PUBLIC HEALTH questions.

Why?

3/
Read 5 tweets
30 Dec 21
LOL

Only at @MassGenBrigham - two of the Top Hospitals in the nation…

@harvardmed@Harvard

Where “breakthroughs” happen daily within the ranks of America’s top doctors

Maybe time for a new marketing approach? :) Image
Here’s the link.

Wonder if/when it’ll change. Not that it needs to or should. Just amusing.

massgeneralbrigham.org
Sorry - if anyone didn’t get the joke - I Was making fun of the use of the word “Breakthrough” as a positive to market just because the word these days is so caught up w Breakthrough Infections.
Read 4 tweets

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