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T. Ryan Gregory 🇨🇦 Profile picture
@TRyanGregory
Nov 16, 2022 • 22 tweets • 8 min read • Read on X
I noted recently that claims about exceptionally high rates of RSV this year, caused by "immunity debt" and explaining the high number of children in hospital, is an empirical claim that requires data. Well, we now have this for Canada thanks to @Wikisteff (follow him btw!). 🧵
Here is a plot of RSV rates since winter 2013/2014. As you can see, it's a very regular seasonal pattern for all the years up to the start of the COVID pandemic. There was essentially no RSV two years ago when schools were closed (winter 2020/2021). Rates of RSV in Canada from...
And it's not just RSV. There was almost no flu or colds caused by other coronaviruses (not SARS2) two years ago either.

So, we can conclude two things right away: 1) mitigations worked extremely well and absolutely crushed respiratory virus transmission, and) the first assumption of "immunity debt" holds, namely that there was a season without kids being infected with RSV or flu.
BUT, look at last year. Winter 2021/2022 was a record season for RSV. It is simply not accurate that we are seeing three years' worth of RSV cases this year. RSV was back last year after many mitigations were lifted. Rates of RSV in Canada from...
Last year, there were lots of cases of RSV but hospitals were not overwhelmed like they are right now. This year, RSV season has started early but the case numbers are not exceptionally high yet. Still, many kids are in the hospital already.
So, this doesn't fit with the simple "immunity debt" hypothesis. Something else seems to be going on. Of course, high rates of severe infection without more cases is consistent with the "immunity theft" hypothesis in which past COVID infection impairs immune function.
But there is another interesting observation pointed out by @Prassas, namely that flu was NOT back last year the way RSV was. Is there something about RSV and flu co-infections that matters? Immunity debt to flu but not RSV? Is flu more severe this year?

We still don't know what exactly is happening. What is pretty clear, though, is that assuming that it's simply "immunity debt" after two years of no RSV infections is false in Canada. This is why we need to test multiple hypotheses and why we need data, not just-so stories.
In the meantime, we *know* that mitigations work against the viruses that are leading to kids becoming very ill and pediatric hospitals being overwhelmed. Whatever the explanation, the right thing to do *right now* is to reduce transmission of these viruses in children. #MaskUp
Again, huge thank you to @Wikisteff for the data sleuthing -- this is exactly what we need. Also, as he noted:

For a bit more on "immunity debt" vs. "immunity theft" (the latter being only a slightly modified-for-catchiness version of @FurnessColin's "immunity robbery").

Don't forget to check out this fantastic discussion on @TheAgenda. Note that a couple of the claims made by Dr. McGeer (three years of RSV all at once after two years without, this only being a problem with pediatric hospitals in Canada) are not accurate.

It bears noting that there *is* a mechanism by which COVID infection can impair defence against RSV.

journals.plos.org/plospathogens/…

frontiersin.org/articles/10.33…

mdpi.com/1999-4915/12/1…

nature.com/articles/s4142…
There was also plenty of RSV in the US last year.

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More from @TRyanGregory

T. Ryan Gregory 🇨🇦 Profile picture
Jun 6
Nimbus (NB.1.8.1) is getting a fair bit of attention, but it's not the only SARS-CoV-2 variant worth watching. Here's a link to info about a few more, all of which have arisen either through within-host evolution during chronic infection and/or within-host recombination.

🧵

1/
First, a reminder that Nimbus (NB.1.8.1) is a triple recombinant with both BA.2.86 and XBB ancestry -- that is, it has multiple recombination events and chronic infections in its evolutionary history. Here's a thread I wrote about it:



2/
Another that is very competitive is XFG, which is a recombinant of two Pirola lineages (LF.7 x LP.8.1.2).

Head over to BlueSky to see the post by Josette Schoenmakers on the XFG vs. NB.1.8.1 battle for dominance.



3/bsky.app/profile/josett…
Read 4 tweets
T. Ryan Gregory 🇨🇦 Profile picture
May 27
Meet "Nimbus", aka SARS-CoV-2 variant NB.1.8.1.

🧵

1/ Diagram showing the ancestry of Nimbus (NB.1.8.1). The evolution of NB.1.8.1 has including three recombination events, including XBB (Kraken) and BA.2.86 (Pirola) lineages.
Evolutionary tree of SARS-CoV-2 variants showing the small fraction of diversity covered by every variant with a Greek letter except "Omicron", and the enormous diversity within "Omicron", including Nimbus NB.1.8.1.
The last variant to receive an informal nickname was BA.2.86 "Pirola" nearly two years ago, back in August 2023. Since then, it has been a prolonged "variant soup" phase, with descendants of BA.2.86 arising, gaining prominence, and then falling in frequency.

2/ Tweet from August 18, 2023 with the nickname "Pirola" for BA.2.86.
A prolonged variant soup phase involving the Pirola clan does not mean there was no within-host evolution occurring. It just meant that nothing had gotten back into the general population that could compete with the many, many descendants of BA.2.86.

3/
Read 14 tweets
T. Ryan Gregory 🇨🇦 Profile picture
Apr 29
Btw folks, what happened is that Québec saved us all from Poilievre. Bloc voters went Liberal this time to keep him out.

Ontario, not so much. Big gains for the Cons.

BC was where the NDP did best last election, and this time it went Lib and Con.
So, we essentially traded a Liberal minority with progressive parties being very influential to a Liberal minority with a huge Conservative opposition and minimal progressive representation.

The fact that 41.4% voted Con (vs. 43.5% Lib) isn't a good sign either.
Yes, I'm relieved that it's not Poilievre as PM and I'm glad he lost his seat. But beyond that, we're not in a very good place overall. The major rightward shift isn't going to be good, especially when the Liberals eventually lose to the Conservatives.
Read 4 tweets
T. Ryan Gregory 🇨🇦 Profile picture
Apr 1
It's very important to be clear about what is happening in the Canadian election and how progressives need to approach it. 🧵

The LPC surge toward a majority is due primarily to a collapse of support for the NDP and Bloc, and much less so a drop in support for the CPC.

1/ Vote and seat projections for Canada.
Vote and seat projections for Ontario.
Vote and seat projections for Québec.
This means that the Libs are mostly picking up progressive voters who are planning to vote strategically to stop the Cons. They are not picking up huge numbers of "moderate conservatives".

Cons support is generally committed but Libs support isn't.



2/angusreid.org/canadian-elect…
The *winning strategy* for Libs is to make strategic voting by progressives as painless as possible by leaning *leftward*.

The winning approach for progressive voters is to make it clear they cannot be taken for granted and do not agree with rightward drift.

3/
Read 6 tweets
T. Ryan Gregory 🇨🇦 Profile picture
Mar 19
Thoughts on pandemics, inclusion, annexation, Indigenous issues, climate, genocide, and more and the connections I see among them. I fully acknowledge that I am writing this from a position of substantial intersectional privilege.

🧵

1/
I really hoped that the (ongoing) SARS-CoV-2 pandemic would inspire us to make meaningful, positive changes in society. Indeed, early on it seemed like privileged people finally understood what it was like to lack access to things we otherwise take for granted.

2/
Sadly, but perhaps predictably, we instead rushed back to the status quo as quickly as we could. If anything, things are worse now in terms of public health, accessibility and inclusion, and global health equity. Infectious disease has been actively normalized.

3/
Read 10 tweets
T. Ryan Gregory 🇨🇦 Profile picture
Mar 8
Please, stop making these terrible arguments in order to dismiss threats of annexation by the US. 🧵

1. "He's just joking, trolling, negotiating, or being Donald."

Clearly not. Stop it.

1/
2. "Trump can't just declare war on Canada."

He wouldn't bother and he doesn't need to. The last time the US formally declared war was 1942. See every US invasion or occupation since WW2.

2/
3. "The US can't invade because of the constitution / international law."

He doesn't care about either of those things. See everything he's currently doing.

3/
Read 10 tweets

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