Thread by @WheatNOil

Are we confused enough about the AstraZeneca thing? I’ll try to write a thread later explaining as best as I can and how we got here.

Just busy with work, parenting, and a massive blizzard right now.

Okay, I’m going to do this in fits and starts between other things.

Clearly there’s some confusion here.

Let’s start with the basics. We should probably explain the difference between Health Canada and NACI.

Health Canada is a government regulatory body. It says if something is safe for use in Canada and what sort of warning labels should go on it, etc.

It answers the question “can we use this vaccine?”

NACI is an advisory committee that provides recommendations for HOW we should use vaccines. It considers science but also economics, ethics, equity, feasibility, and acceptability.

Health Canada says you can use Vaccines X, Y & Z

NACI says who should get them & when, as example

So these two bodies may not say the exact same thing because their roles are slightly different.

Health Canada says AstraZeneca is safe for 18+.

NACI says, yeah we get that, but maybe let’s pause the <55 crowd & focus on 55+ for a bit until we get a bit more data here.

This is not the first two these two bodies weren’t providing the exact same guidance with AZ specifically.

Health Canada approved AZ for 18+.

NACI said, maybe hold off on 65+.

NACI never said AZ was unsafe or ineffective in 65+. They just wanted more data.

Then NACI reviewed more real world data and said “oh yeah, 65+ looks good, let’s go!”

Health Canada maintained 18+ throughout.

So then a few of reports of blood clots came out. Some European countries paused the rollout.

This thread at the time remains essentially true. The blood clots were very rare & not clearly above the rate people normally get blood clots.

https://twitter.com/wheatnoil/status/1370747222644592641

It remains true that ‘getting’ COVID is a MUCH greater risk of clotting than getting the AZ vaccine.

It remains true that people, generally, get clots at a higher or equal rate by simply living than by getting the vaccine. The clots here are extremely rare.

However, the general rate of clots isn’t the same by age. Your risk of clotting is much higher as you get older. Clotting at a younger age does happen, but it’s more rare. And there are reports of some younger people getting clots. Still rare, but there are legit reports.

How common are these clots? Well... that’s kind of the question.

Initially thought to be 1 in a million. Now Germany reports 1 in 100,000. So 0.001%.

What’s the true rate? Unclear. Rare but the exact number isn’t known. That’s part of the reason for the pause.

Now, this is where NACI comes in. Clearly if you’re above 55, the risk of death, let alone the risk of clots, is much higher with COVID.

The increase risk of clots is minimal. Avoiding the vaccine is FAR more likely to kill you than taking it. It’s not close.

Hence, NACI saying, yeah go ahead and vaccinate if you’re over 55. The risks are minimal. The benefits are huge.

The UK has had massive success by vaccinating mostly people over 55 so far.

(More coming, bed time story time for 7yo)

Ok, so what about the under 55 group?

Well, this group has a few things going on. For one, younger people clot less at baseline. So more clots there is more notable. Also, their risk from COVID is less than those over 55.

Now, even with these reports of clots, there’s ‘still’ not enough evidence that your risk of clotting is higher by taking the vaccine. That’s how rare they appear to be. That’s why Health Canada hasn’t changed its approval. It’s still 18+.

But NACI is saying, “let’s hold on a moment”. We have a group that’s less at risk from COVID ‘and’ we have other vaccines available. We can afford to pause and look at these few cases more closely.

Is there something these few going people with clots have in common? Are they taking some other drugs? Do they have some known disorder? How common is this rare event exactly?

NACI is looking to answer questions like that.

You’ll note, not every country has come to the same decisij to pause. That’s because we do things that carry risk all the time.

If you take a birth control pill, your risk of clots is likely higher than anything from the vaccine. Same with smoking. Same with taking an airplane.

*decision

Autocorrect, what the hell is a decisij?

NACI is making this recommendation based on the fact that we have a metric shit ton of Moderna and Pfizer coming in, so we can afford to pause the AZ on a group of people (who mostly aren’t getting it yet anyways), until they can review more data. Like they did with the 65+.

It’s precautionary & evidence that they’re being abundantly cautious. Maybe overly. It’s a judgement call by the expert group taking into account the full context of the vaccination effort.

They’re not saying AZ is unsafe for <55. They’re saying can we look at these cases first.

It’s also worth noting that this isn’t evidence the vaccine was rushed. These events are so rare, that no amount of trials would’ve likely picked it up.

It’s something that only shows itself when you’re vaccinating millions.

As practical advice, these rare events appear to occur between 4 and 20 days post vaccine. So if you got the vaccine 3 weeks ago, you’re out of the window.

Like most potential vaccine side effects, it shows up quickly, not late onset.

Finally, I understand people who are worried. We all would like to accept no risk. But ‘not’ getting the vaccine is also risky. Not getting the vaccine can literally kill you.

For the record, my own mother got AstraZeneca last week. I do have a vested interest in its safety.

Finally finally, most of you know this, but immunology is not my area of expertise. I claim no special knowledge here. Just trying to explain and translate the decisions made by the actual experts so people can understand. As always, where I’m wrong, I’ll happily correct.

Oh, one thing I forgot to add: so far, there are zero (0) reported cases of this type of clot associated with the vaccine in Canada.

So this is certainly a precautionary decision.