Michael Mina Profile picture
Epidemiologist, Immunologist, Physician, Harvard Public Health/Medical School. Discuss vaccines, immunity, infectious diseases, public health, and tests
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6 Oct
THREAD: Some thoughts on this White House Report on Testing...

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The extra $1B towards purchasing rapid tests is a great step forward. It is a strong signal that the WH and the Federal government is recognizing that American's are demanding to be able to know if they are infectious in real time.

So I'm fully supportive of the WH support

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A question was just asked to @CDCDirector about whether roll out of rapid tests will limit the public health reporting

This is an important question and a good reason the federal government should simultaneously prop up efforts to make these tests verifiable and reported.

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Read 7 tweets
6 Oct
HUGE News!

White House finally recognizing crucial need for rapid tests as we get through this most recent wave of COVID (& after 700K lives lost)

This is good news & a show of support for public health from the White House and the FDA

However...

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washingtonpost.com/health/2021/10…
We Should be careful to take this in stride. We've seen similar announcements in the past. FDA press release, media attention, WH remarks and then little to no change.

The FDA EUA for ACON rapid tests is a terrific step forward!!

But is it enough...?
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I would argue that it is not enough. There are many many many very high quality tests out in the world that simply do not exist in the US market bc of the approach we take to regulating these tests.

As I've mentioned in the past...

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Read 8 tweets
1 Oct
1/ Thread

While vaccines are most effective tool to protect us all from severe disease

#RapidTests answering “Am I Infectious Now?” are an answer to society *living* with Covid-19

New @NYTOpinion @nytimes by me and Steven Philips @TheCOVIDCollab

nytimes.com/2021/10/01/opi…
@nytopinion @nytimes @TheCOVIDCollab 2/

FINALLY Americans are seeing the value of at-home rapid tests, and demanding them to help keep their families, friends, neighbors safe and schools and businesses running.

But now the US govt needs to make more highly accurate rapid tests available to meet that demand.
@nytopinion @nytimes @TheCOVIDCollab 3/

In many parts of world, rapid testing is commonplace. Policymakers recognized early that rapid tests could blunt the pandemic by scuttling transmission chains. They created special regulatory pathways to evaluate these tests, quickly & effectively

nytimes.com/2021/06/09/wor….
Read 11 tweets
24 Sep
Thread On tests and the media

It is almost universal that any piece discussing Rapid Ag tests says “PCR is more accurate but…”

But even this isn’t true. It simply depends what you want to detect.

If wanting to identify ppl who are contagious, PCR is much less accurate.

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If your goal is to detect ppl are infectious, a rapid Ag test is highly sensitive AND specific for this.

PCR is not specific for this. It will read positive even when not infectious. So… it’s less accurate for the public health question at hand “am I infectious”

2/
You might say… well PCR is much more sensitive. But even that is not true. A bit more, yes, but if wanting to catch infectious ppl, it’s really but that much more sensitive and, if that’s your goal, then PCR is massively LESS effective than a rapid test.

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Read 7 tweets
19 Sep
@MarkZlochin @CircusPubes @DrPathHero1 yes.

A very important piece is the temporal relationship between when viral RNA is highest, when antigen tests are highest sensitivity and when people are most likely to be infectious following exposure. While almost no studies directly observe all three together...
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@MarkZlochin @CircusPubes @DrPathHero1 They all fall directly in line with the exact same time period after exposure or - when symptoms are demonstrated, with the same period surrounding onset of symptoms.

So we really do not need empirical data showing transmission and viral load since the kinetics show it all

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@MarkZlochin @CircusPubes @DrPathHero1 A major problem obtaining the direct empirical data is that if someone is testing, they likely aren't infecting others. So, people who are infecting others, you simply are not getting their swab at the same time as they are infecting. So relationships are skewed.
Read 5 tweets
17 Sep
To battle COVID, Biden's Action Plan boldy calls for scaling rapid tests! & requires millions of Americans to vaccinate or test

But now the timer is set. W/out immediate change, we will see PCR delays of 3-10 days & rapid test shelves remain largely empty

We can avoid this.
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Luckily, the issue is a simple one to fix (all things considered).

The tests exist in HUGE numbers across the globe. Just not in the US. The reason? We've asked the FDA to take on an impossible task... to evaluate high quality PUBLIC HEALTH tools, when this is not their job

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The FDA evaluates medical devices - and does not evaluate public health tools

This is THE problem. As long as we consider rapid tests as medical devices (they're not - they're PUBLIC HEALTH transmission detection tools) FDA is forced to fit a square peg in a round hole

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Read 8 tweets
16 Sep
DILEMMA

Its common to say ALL kids mask during school, w out mention of daily rapid tests for entry

Yet, it’s heresy to suggest ALL kids test daily and go maskless

- Poor fitting Masks cut transmission, maybe <50%

- Rapid tests cut risk of infectious entering by >90%
I’m NOT suggesting we not do both. But dilemma is:

Why is it that when masks are discussed, rapid tests in AM are not. BUT when rapid tests in AM are discussed, it has to always be followed by “And masks too”.

Demonstrates group think rather than science backed decisions

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We DO need rapid test supply. Many ways to make it happen. Change of how they are designated (as a public health tool) is first step in my view so that we can massively accelerate access and scale

Read 5 tweets
15 Sep
Rapid tests work very well to answer 🧵
AM I INFECTIOUS and a RISK TO OTHERS

This is THE public health ? we care about

I made a BIG chart of rapid tests

- Overall sensitivity vs any PCR pos - what FDA judges

- Sensitivity if infectious (97%!) - what we actually care about

1/ Image
This data above comes from the UK COVID-19 Lateral Flow Oversight Team.

What the data above shows is that rapid tests are excellent public health tools to quickly identify almost anyone who is currently infectious and needs to isolate

What it also shows is...
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This shows why there is so much damn confusion about if rapid tests are sensitive

Answer: YES they are... if the question is "Am I Infectious Now and do I need to isolate"

However, if we compare them to PCR, then we are asking a different question: Do I have any RNA in me

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Read 13 tweets
11 Sep
Notes on sensitivity of rapid Ag tests for what matters: detecting infectious ppl

Sensitivity:

- Highly infectious (ie superspreader levels): >99%

- Moderately infectious (ie infect 2 or 3 ppl in a classroom): 90-95%

- Mildly infectious (ie spread to spouse only) ~80-90%

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This Graph of viral load over time helps to explain this sensitivity issue: Image
Further, symptoms vs no symptoms has no impact on test performance. Studies that say it does are not recognizing the sampling bias that enters their studies.

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Read 5 tweets
9 Sep
This is tremendously good news! (Thread)

@POTUS fully supporting scale up of rapid at-home tests

I've been arguing for this - the Defense Productions Act to be invoked since early last year to drive production of rapid tests

Testing in a pandemic is a Public Health need

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While I am tremendously happy to hear the President say this.

I do have my reservations:

Time is of the essence. If we start the scaling process now, it will take a long time.

Meanwhile many many tests exist globally. We could be using those for the time being.

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Importantly, I worry that the 280 million tests that are going to be purchased and produced with the use of the DPA... well, that's less than one test per person over the course of a year. The number sounds big but we do have 330 million ppl in US.

But it is a great start!

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Read 10 tweets
7 Sep
Dear @POTUS Biden,

The US is at a critical point & we need greater access to faster tests

Rapid tests are barely available bc they're regulated here as MEDICAL tools-holding them back

Please write an EO that makes COVID testing in US a Public Health good

Thanks
Ppl of the USA
These tests are regulated by FDA as medical devices. Which has greatly limited them!

For pandemic control UNDER AN EUA FOR A PUBLIC HEALTH EMERGENCY, rapid tests should be regulated as critical public health tools, vetted (appropriately) by CDC/NIH.
I had the opportunity to speak to the prior administration about this. Unfortunately it didn't go far despite many ppl trying.

I hope that an administration as forward looking as yours (@POTUS ) would see the benefit of an executive order that stops this deadly silliness.
Read 4 tweets
7 Sep
Did you know:

A test *not* performed has a sensitivity of 0% for symptomatic and asymptomatic ppl

A test w a 48 hr delay has 0% during the days of waiting

I talk a lot about sensitivity- but if we want to detect infectious people - frequency of testing is even more important.
And of course, the papers to back it up:

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nejm.org/doi/full/10.10…
And Test Sensitivity is secondary (way down the list) to frequency and turnaround time for using testing as a public health tool.

science.org/doi/10.1126/sc…
Read 5 tweets
7 Sep
Did you know

A test that is 100% accurate to detect infectious ppl will only *APPEAR* to be 30%-60% sensitive when compared to PCR-particularly asymptomatics

Why?

PCR stays positive LONG AFTER contagious period

for Public Health, PCR is NOT Specific - it’s a wrong comparison
Although rapid tests are not 100% sensitive to detect infectious levels of virus, they are >95% and do approach 100% for “superspreader” levels of virus.

We just (ignorantly) continue to compare them to PCR - which has led to massive confusion.

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This issue with PCR has caused us to isolate millions of ppl who were no longer infectious and lead contact tracers to trace and quarantine many many millions who were never exposed.

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Read 6 tweets
7 Sep
With all the news of vaccines & immunity, did you know measles infections destroy immunity and cause “Immune Amnesia”, increasing risk of all other infections

Our research in ‘15 & ‘19 discovered this & the abbreviated story is written up nicely here:

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medicalrepublic.com.au/the-great-meas…
In 2015, along w Bryan Grenfell and colleagues, we discovered an exceptionally strong relationship between measles epidemics and all cause childhood mortality - following outbreaks of measles, child mortality was increased for 2-3 years.

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science.org/doi/abs/10.112…
We hypothesized then that measles was destroying B cells and plasma cells responsible for retaining immune memory. This is bc the measles virus specifically attacks immune memory cells via attachment to CD150 - a protein enriched on memory cells.

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nature.com/articles/ni010…

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Read 10 tweets
4 Sep
I’ll say it again:

Rapid tests have the same accuracy in asymptomatics as symptomatics

If someone says they are less sensitive to detect infectious people who are asymptomatic, they are wrong

The test does not care about your symptoms, it cares about how much virus you have
The above comment is referring to “same accuracy to identify infectious individuals”.

The reason numerous papers say they are less accurate in asymptomatics is because of sampling bias. Asymptomatics are much more frequently tested *AFTER* they are no longer infectious.
s PCR remains positive for weeks, meanwhile infectiousness lasts only 3-7 days - and thus rapid tests are only positive for 3-7 days or About 30% of the time that ppl are PCR positive.

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Read 4 tweets
31 Aug
No!! We don’t need stricter quarantine! We need smarter control!

Please, do not quarantine whole classes when a student turns positive. Kids have had enough! We all have.

Test to stay!

Get LA to lobby increased access to rapid tests for public health!

latimes.com/california/sto…
Test to stay is simple - and evidence based!

Instead of quarantine, rapid test at-home each AM before school. It is 1 minute of hands on time in the morning before breakfast or after brushing your teeth.

If negative, go to school. Do that for 7 days instead of quarantine.
If we don’t wants to base at-home testing on the honor principle, then use eMed to get verified results via at-home testing. It works!

We have the knowledge and tools to keep our society and schools in particular running smoothly in a pandemic
Read 4 tweets
7 Jun
I wrote this 🧵 👇and appreciate the many comments so far.

I want to comment in a new 🧵 here on Why we should encourage Antibody testing for those who are interested.

Or at least not recommend against it, as our FDA is currently doing.

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First - we do not yet have all the information about what exactly an Antibody titer specifically means post vaccine in terms of protection.

So making a binary assessment of protection, or lack of protection based on antibody titers at this moment isn’t necessarily wise

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But just bc we don’t currently have all the correlates of protection worked out now, doesn’t mean we shouldn’t gather Ab information today for our future selves.

We are in the middle of a pandemic. Science is moving FAST! In 6 months we may wish we had our early Ab titers

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Read 10 tweets
7 Jun
Decision to recommend against antibody test after vaccination is yet another poor decision.

If CDC/FDA willing to say that full vaccination = immunity, then there is no good reason to say antibody positivity after vaccination does not equal immunity

1/

fda.gov/medical-device…
So on the positive side, if just getting a vaccine implies immunity per, then a positive response after a vaccine that is detectable by antibodies should imply that the person was vaccinated - thus protected.

But...

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But..on negative side - if someone fails to seroconvert to positive on EUA authorized Ab tests after vaccination... this would be crucial knowledge for someone to have and to talk to their doctor about.

FDA should be encouraging Ab testing post vaccine - esp serial measures

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Read 8 tweets
30 May
It’s hard not to feel complicit.

As high income nations squabble over whether to vaccinate the youngest and least vulnerable, much of the world has yet to vaccinate their absolute most vulnerable.

Global inequities run deep. But this is a particularly egregious one.
Again, these are optimization problems.

We should ask questions like: how many childhood doses are worth a single dose in a 70 year old in India.

Probably you need thousands of childhood doses to offer as much benefit as a single dose to a 70 year old.
Of course, these are not just simple public health decisions that need to be optimized - these are massive geopolitical (mis?)calculations that are above my pay grade.

That or just frank ethnocentric behavior.

Probably a bit of both.
Read 4 tweets
29 May
Rapid testing found 10% of the cases in Nova Scotia

IMPORTANTLY, that 10% was almost entirely ppl currently infectious and actually needing to isolate.

So the *relative effectiveness* of the rapid testing is much greater than 10%.

nationalpost-com.cdn.ampproject.org/c/s/nationalpo…
Just to be clear: 10% of the *detected* cases. Of course there were many more cases that no test picked up.
“If they had waited until they developed symptoms to get a PCR test, and then waited another 24 hours until they got the PCR results, that’s at least two days where they might have been unknowingly spreading the virus.”
Read 5 tweets
28 May
We have vaccines. But it doesn’t mean we stop caring to see where the virus is and adapt quickly if and when outbreaks take off.

Rapid accessible tests are not just tests. They represent real time accessible information on the virus in and around us.

time.com/6050846/covid-…
The type of testing we will need in a well vaccinated population isn’t the frequent rapid testing I’ve called on for a year.

I don’t want us to remain in testing purgatory.

The landscape is changing and so too is the type of testing that will be useful...

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We will now move into a type of testing that is more targeted.

Less about suppressing massive outbreaks and more about having the tools to respond *effectively* if and when they arise.

Tools that allow us to not have to close anything down - but test to stay open.

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Read 9 tweets