Michael Mina Profile picture
Dec 27, 2021 12 tweets 4 min read Twitter logo Read on Twitter
CDC’s new guidance to drop isolation of positives to 5 days without a negative test is reckless

Some ppl stay infectious 3 days,Some 12

I absolutely don’t want to sit next to someone who turned Pos 5 days ago and hasnt tested Neg

Test Neg to leave isolation early is just smart
I am 100% for getting people to drop isolation early.

Heck, I formally recommended it to CDC in May 2020 and Published the recommendation in J of Clin Infectious Diseases in April 2020.

But it was always with a negative test.

What the heck are we doing here?

This is the part that hurts the most. The reason they are doing this:

"The change is motivated by science demonstrating... SARS-CoV-2 transmission occurs... generally in the 1-2 days prior to onset of symptoms and the 2-3 days after"


Today, it is OBVIOUS the situation has changed.

Ppl are testing earlier b/c symptom onset is early - no longer two days after people are infectious.

So now people are staying positive even longer after testing positive, because they find out earlier they are positive.

And by positive I don't mean PCR positive. I mean rapid antigen test positive for days longer. Often more than 10 days.

So to say, leave isolation regardless of if you have a positive antigen test is remarkable.

Someone KNOWN to be Pos for 5 days is, in my view, still one of the highest risk individuals in society for onward spread. We do SO much just to find ppl who are positive in first place. When we do identify them, we should do everything possible to keep them from spreading

At least, If leaving isolation at 5 days w/out Neg test - WEAR N95 or similar performing mask

Govn't should provide them to everyone who enters isolation (along with a rapid test!)

If entering isolation - click a button & get N95 & rapid test SIMPLE

@linseymarr @kprather88
This is but one of a nearly limitless set of examples of how reckless this decision is.

The thing that really hurts me the most - is that not requiring a positive rapid test to leave isolation is probably linked to a perception of not having enough rapid tests in the US...

Which is obviously a massive problem in its own right but one that is EASILY changed.

We CAN get the tests

We CAN. Many countries are getting these and more.

This doesn't have to be a hard decision:

In Isolation? Yes --> Click a button --> Get 2 rapid tests delivered to you for free for use on day 5 and if still neg on day 6, exit.

A good example - among so so many of why rote removal from isolate without a negative test is just not a smart public health move.

We put all this effort into discovering infectious people... why not at LEAST ensure those we do discover don't spread on.

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More from @michaelmina_lab

Nov 28
Does halving a vax booster dose make a difference to protection?

It shouldn’t

But could lower adverse effects

New @TheLancet paper is a great reminder that the immune system works on exponential scales

Halving the dose has min impact

Compare blue vs orange (half) per group https://www.thelancet.com/journals/lanwpc/article/PIIS2666-6065(23)00271-7/fulltext#secsectitle0010  No impact between a full dose (in blue) compared to a half dose (orange) in various prime boost groupings.
The paper is a great demonstration of the studies to perform in order to enhance vaccine distribution & access globally

If in emergencies we halve doses could we drive costs down and massively increase access??

Immune kinetics suggests so.

This is a bit like Ct values on a PCR test.

You can perform two swabs. One can be only half as effective as the first - and it only amounts to a single Ct difference.

One could be a full 90% less efficient and it’s still only 3Cts different!

We often gloss over exponential
Read 4 tweets
Nov 27
You can extract more information from rapid antigen tests than you may realize

How quickly or slowly the test takes to turn positive, and how dark the line gets can help to understand how much virus you have in your sample.

Here’s a diagram I made to describe it.
Importantly, the amount of virus on your sample is only one aspect of an infection and infectiousness

Some ppl may be infected but have no virus in their nose, for example, and not detectable on any nasal swab test including PCR - Probably not particularly infectous if so.
Others could be starting to become infectious but not yet positive on a nasal swab is another example. In that case it highlights of course that any test gives you a snapshot in time.
Read 4 tweets
Nov 13
Wondering if you should get your baby the new RSV shot?

I’ve studied respiratory viruses like RSV, and their vaccines and treatments for years

Here’s a 🧵 of key info

We just had a baby last week

We chose to protect our newborn with it

And we’re lucky we could get a dose

1) First and most critical is that the new RSV shot is very protective against RSV

In large placebo controlled “gold standard” trials it was ~75% effective to prevent RSV requiring medical attention in babies


2. It’s Safe

There were no indications of increased serious adverse events associated with the shot

In fact, there was a very small decrease in the number of serious adverse events in those who received the shot compared to those who got placebo

3/ Image
Read 12 tweets
May 20
Soon, any lab will be able to synthesize their own DNA molecules

So too will ppl at home, much like how 3D printers are much more accessible

Great for innovation
Terrifying for biosecurity

Will be very tough to keep checks to prevent “homemade” viruses

To place in context, today synthetic DNA is made MANY reasons

Labs usually order it from companies that are required to check to make sure nefarious sequences are not being ordered

I’ve experienced this myself when getting *pieces* of smallpox DNA synthesized

But as the instruments become simpler, smaller and less centralized, maintaining those checks will become difficult or impossible

The technology will need to be built w screeners against databases of known “agents of concern” and flag them

But surely these will be hacked
Read 6 tweets
May 14
Very important & massively sad how long it took

@CDCgov publishes guidance on indoor air quality to help keep spaces healthy

While the guidance is directed at COVID-19 (oddly the day after the PHE ends…) it will help health overall far beyond COVID

cdc.gov/coronavirus/20… Image
These are some of the highlights of the new recommendations
/ guidance

2/ Image
3/ Image
Read 5 tweets
Apr 26
This is a decent article

But time to just be blunt - the data from the repeat infection papers from the VA are hugely misleading

A single, major bias makes the conclusions wildly off

The denominator of total repeat infections is massively off!


The authors look only at 2nd, 3rd, 4th infections that cause disease enough to cause someone to drive to the VA hospital and get a test

The population funnel down from 1 to 3 infections spans multiple order of magnitude - and this drives massive bias!

0 infections - >1M people
1st infection - 100,000’s of ppl
2nd - 10,000’s
3rd - 1000’s
4th - 100’s

What they completely fail to discuss are the 100’s of thousands of ppl who get repeat infections and clear it w/out issue

Read 5 tweets

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