Michael Mina Profile picture
Sep 30, 2020 11 tweets 4 min read Read on X
To detect #COVID19 before it spreads to others, we need frequent accessible testing.

We cannot detect pre/asymptomatic people before they spread if we do not test frequently.

A new article in @NEJM by ⁦@DanLarremore⁩, Roy Parker and Me

1/x nejm.org/doi/full/10.10…
An ideal screening test is one with high sensitivity.

During a pandemic of a fast moving virus that transmits asymptomatically, it is difficult to detect people before they transmit to others.

2/x
This far we have focused almost all of our screening efforts on the use of the very sensitive (and specific - a good thing) qPCR.

The qPCR meets the molecular needs of detecting this virus. It has an extraordinary sensitivity.

But it is extremely limited

3/x
Focusing on PCR as a screening method today necessarily equates to low frequency screening.

With a virus that transmits before people feels symptoms, low frequency testing equates to missing the infectious stage of most people’s infections. Catching them too late, or never.

4/x
So in the @NEJM piece, we suggest that the goal should shift away from the sensitivity of the test to detect molecules and towards the sensitivity of the testing program to find infectious people and filter them out before infecting others.

5/x
In other words, we want to focus on the *sensitivity of the testing regime* to detect and stop transmission, rather than focus on the analytical sensitivity of the test to find molecules in the relatively small number of samples that can be reasonably tested.

6/x
The PCR test is wonderful and has a terrific sensitivity. But it comes at the expense of being very limited.

In short, the best test in the world with the highest molecular sensitivity has a near zero % sensitivity to detect infectious people if it can barely be used.

7/x
If the world can create cheaper faster tests that can be produced and distributed to millions of people and used frequently, then the greater frequency more than makes up for the potentially lower molecular sensitivity of the frequent and accessible tests.

8/x
Ultimately this means that a low molecular sensitivity test that is used very frequently by many people will have a MUCH greater *sensitivity to catch infectious people* before they have a chance to spread virus to others.

To put this in perspective...

9/x
Collectively, in US, our screening programs based on high molecular sensitivity PCR likely catch less than <5% of infectious people in time to act and prevent them from spreading.

Thus, our PCR based testing has a <5% sensitivity to detect #COVID19 before it spreads.

10/x
This is why we must rethink the meaning of sensitivity of #COVID19 tests. We must move away from thinking just about the ability to detect molecules and towards the ability to detect infectious people.

The sensitivity of the testing program must be high - not the test.

@US_FDA

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More from @michaelmina_lab

Jun 12
I've been thinking on my review of RFK Jrs 8 new ACIP members

When announced, I found myself thinking "could've been much worse" and so was relatively favorable

However, the bar being set so low caused me to miss a huge piece... and there's still great risk!

Short thread
1)
While I was pretty favorable to a majority of the new members - the bar is set inredibly low -

I was just happy the 8 were not the most hard core ideologues for whom destroying vaccines is practically religion (like RFK Jr)

That obscured the biggest problem of the group

2/
Perhaps the biggest problem is it is a panel of people who, generally speaking, are generally NOT:

experts in diseases vaccines prevent
experts in vaccines
infectious disease epidemiology
clinical trials

If this was the private sector, no way would this group pass muster

3/
Read 6 tweets
Jun 12
RFK Jr released names of 8 ppl he is placing into ACIP to replace 17 removed

Actually a majority are v reasonable - 2 of 8 however align heavily w conspiracy & anti-vax but as I discuss, their presence may have a silver lining

My thoughts:
Thread



1/cnbc.com/amp/2025/06/11…
Joseph Hibbeln MD has long researched and advocated for optimizing nutrition, including studying things like seafood consumption in pregnancy and role of mercury consumption and whether it is linked to autism. Generally he’s come out saying it’s not.

Summary: No evidence of anti science or anti vaccine. Likely very balanced and nuanced rigorous scientist to serve on ACIP. 
2/
Cody Meissner MD
Is a pediatric infectious disease expert at my Alma mater - Dartmouth. He is a rigorous scientist and has defended vaccines while formally recognizing underlying issues that are causing people to turn away from them - such as vaccine success driving down disease - affording people the luxury of focusing on very rare side effects while forgetting the real impacts of the diseases. 

For example in @NEJM he wrote: 

Summary. Terrific Choice

3/Image
Read 11 tweets
Feb 26
This is horrible & exactly what we are afraid of - measles kills ppl

In ~100 infections in TX, someone has already died

For those w/out vacc- it is not the benign virus you’ve been told

1:5 hospitalized
1:100-1000 die

This will spread further.

1/

apnews.com/article/measle…
The measles vaccine is exceedingly safe

It stops infections & spread extremely well!!

Measles on the other hand

1) kills 1:100-1000
2) hospitalizes 1:5
3) Kills immune cells & deletes protection against other infections
4) causes early immune suppression / coinfections

2/
I am extremely concerned that the communities of vaccine hesitancy have grown enough that they are now “bleeding into each other”

Which means infection in one may well ignite outbreaks of many thousands

That will come w more disease and death

Vaccination will prevent this

3/
Read 4 tweets
Feb 19
Measles cases may likely grow into the 1000’s

The TX measles outbreak continues

With “bubbles” of undervaccination getting bigger, we can expect outbreaks in one to catch on to the next

Igniting transmission that may catch and spread across the U.S.

cnn.com/2025/02/18/hea…
One of the most common tropes is that measles is fine & doesn’t cause damage…

This is highly inaccurate

Measles literally grows by infecting and killing memory immune cells. It causes loss to existing immunity creating vulnerabilities & acute damage that is often severe

2/
To discover the massive-stealth-impact measles has on immune protection against infections not associated w measles, we looked at what happened in populations after measles outbreaks swept through, decade after decade across nations…

What we found was astonishing…

3/
Read 19 tweets
Dec 27, 2024
Important wake up call:

#H5N1 BirdFlu just sequenced by @CDCgov from severe Louisiana patient

Most important, the H5 virus mutated inside the single patient to gain an ability to bind human receptors in the upper respiratory tract

It takes just one…

cdc.gov/bird-flu/spotl…Image
This is exactly the type of thing we worry about.

The mutations developed anew in this patient have been linked to severe cases elsewhere

Thank goodness the patient didnt (as far as we know) spread to any people or wildlife but this is the real concern…

We must do better

2/
And what should we do… there are many things we (USGov) should be doing yet barely have:
Read 6 tweets
Oct 3, 2024
🧵 On Seasonality:
SARS-CoV-2 has "seasonality" as a contributor to transmission dynamics

People often refute it - So I made graphs and this thread

NOTE: Seasonality does NOT = "just a cold"
Many of worst viruses have seasonality

Transmission Dynamics ≠ Pathogenicity

1/Image
Image
Image
The first figure is Wastewater SARS-CoV-2 RNA levels averaged across the whole United States

See the REMARKABLE stability in the winter peak

The peak happens in the exact same week each year

Additionally, the start up the upswing to the peak (triangles) is also consistent

2/Image
A common misconception is that "Seasonality" means "no transmission out of season"

That is NOT TRUE

Seasonal forces are those that drive predictable behavior - like a winter peak in the first week of each year

3/
Read 14 tweets

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