Yes, the AstraZeneca vaccine-thrombosis association is causal.

The temporal relationship is strong, it’s not seen with mRNA vaccines, and there’s a plausible mechanism analogous to heparin-induced thrombocytopenia (HIT)

nejm.org/doi/full/10.10…
As with HIT, these are unusual clots: they occur in odd places (brain, abdomen) and in arteries as well as veins.

They’re more serious than the run-of-the mill clots we see all the time.
What's the risk? This has been a bit of a moving target, but it seems to be on the order of 1 in 100,000.

It's possible some cases have been missed, especially in older people.

Still, fair to call it very rare.
With all the buzz and mixed messaging around this issue, many are now reluctant to receive the AZ vaccine.

This is understandable. People are risk-averse by nature.

But it's important to view the risk in context.
“I’ll pass on the vaccine. My risk of dying from COVID is low."

This is a take I've heard more than once.

This framing is faulty because it neglects the other downsides of COVID—hospitalization, spending a week or more on a ventilator, and so on.
Your risk of a bad outcome with COVID depends heavily on two things: your age, and your likelihood of contracting the virus in the first place.

You're 25 and living in a Unabomber-style cabin in rural Montana? By all means, take a pass.
You're 61 and living in Toronto? Different story altogether.

Especially if you spend a lot of time around others, either at work or home.
To weigh the risks and benefits for yourself, it's worth checking out this resource from the Winton Centre for Risk and Evidence Communication (not on Twitter, apparently) at @Cambridge_Uni

wintoncentre.maths.cam.ac.uk/news/communica…
Here's their assessment of the potential benefits and harms by age when the risk of exposure is low
Here's the calculus when the risk of exposure increases to "medium"
And here's when the risk of exposure is high
Reasonable people can disagree on the age threshold below which the potential risk of an unusual clot isn't worth the potential benefits of vaccination.

Even regulators disagree on this.

Anyway, my point is don't be spooked by scary headlines and mixed messages.

Every drug has potential harms, and the AZ vaccine is no different. It's just important to place them in context.

/ end

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More from @DavidJuurlink

5 Mar
Carbapenem antibiotics reduce valproic acid (VPA) concentrations quickly and dramatically

Why does this happen?

/1
The carbapenem-VPA interaction was first described in 1997

Here, an 8-year-old girl with a seizure disorder and pneumonia is treated with panipenem

Thereafter, her [VPA] falls from 30.1 µg/mL (209 µM) to 1.53 µg/mL (11 µM)

academic.oup.com/jac/article/39…

/2
There are many similar reports, all with the same theme:

A rapid, dramatic drop in [VPA], often accompanied by a loss of seizure control

journals.lww.com/drug-monitorin…

/3
Read 11 tweets
7 Jan
This report of a physician who died after receiving COVID vaccine offers a useful lesson in the importance of thinking more critically about does and what does not constitute a drug reaction.

/1

usatoday.com/story/news/hea…
Briefly, the MD noticed petechiae (tiny areas of bleeding into the skin, as seen in image) 3 days after vaccination. He was diagnosed with ITP (immune thrombocytopenic purpura).

People with ITP have profoundly low platelets and can bleed spontaneously as a result.

/2 Image
The temptation to blame the vaccine is understandable: we’re hypervigilant about the safety of new drugs (especially high-profile ones employing a novel technology), and the timing seems like a slam dunk.

But step back for a moment.

/3
Read 10 tweets
6 Jul 20
This thread of drug-specific tips has generated a series of podcasts with @JAMA_current's Ed Livingston (@ehlJAMA). I'll append them here as they are released.
First up: penicillin allergy edhub.ama-assn.org/jn-learning/au…
And here's @JAMANetwork excellent resource on penicillin allergy testing edhub.ama-assn.org/jn-learning/pa…
Read 5 tweets
18 May 19
I'd like to share some reflections on the death of a patient. I’ve thought about her a lot.

She gave me explicit consent to tweet the details of her case, about four hours before she died. Her hope was that someone might benefit from her experience.

/1
She came to hospital as octogenarians often do: with generalized weakness, falls, poor oral intake, fever, hypotension.

Her WBC was 17,000. Blood cultures grew E. coli.

Sepsis. Fixable enough.

/2
But she also complained of pain in her groin and thigh. It was new, progressive and debilitating.

Even moving around in her hospital bed was agonizing.

/3
Read 22 tweets

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