Getting a bit annoyed at everyone using numbers from yesterday’s Oxford pre-print to compare how often CVST occurs after mRNA vaccines and AstraZeneca vaccine.
We cannot directly compare these numbers because they came about in completely different ways.
The authors say so themselves IN the preprint:
"we cannot directly compare the risks of CVT associated with ChAdOx1 nCoV-19 with any of the other vaccines, or with COVID-19, since we are using data collected by the EMA monitoring system, not from the electronic health records..."
And yes, @UniofOxford press release does exactly that anyway:
"Compared to the AZ-Oxford vaccine, the risk of a CVT from COVID-19 is about 8 times greater."

This is one reason (of many) why we need science journalists and not just press releases.

ox.ac.uk/news/2021-04-1…
@UniofOxford So do mRNA vaccines increase risk of CVST compared to the general population?
Let’s hear the authors:
"we cannot conclude that the mRNA vaccines studied here are associated with an increased ris kof CVT; far larger samples are needed to address this question."
@UniofOxford So basically what most people seem to be taking away from this paper (at least in my timeline) and what the press release suggests is directly opposed to what the authors say in the paper.
I do wonder why @SMC_London decided to highlight this particular preprint with a presser.

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More from @kakape

15 Apr
There is an interesting new preprint out that will probably generate a lot of coverage at least in the UK. Essentially it argues that the risk of CVST is much higher from #covid19 than from vaccines.
Quick thread on this:

osf.io/a9jdq/
Here is an image from the paper that is likely to feature heavily in debates around this.
As you can see the risk of CVST here seems to be 8-10 times higher in people with CVST than in people who received mRNA vaccines or AstraZeneca.
BUT: A lot of caveats here.
First of all:
The paper really only makes a like-with-like comparison with mRNA vaccines (as authors pointed out in presser this morning too: “I think our data say actually nothing about the AZ vaccine.”).
That’s why the data on AstraZeneca is greyed out in that graph.
Read 11 tweets
14 Apr
Most fascinating bit of ACIP meeting so far is a detail on the 25-year old male in J&J trial, who developed CVST with hemorrhage after 8 days.
J&J representative says it was retrospectively determined that he was negative for anti-PF4 antibodies before vaccination, positive after
Case reports are fascinating.
Here are some details on the case from previous tweet.
(Short sentence on anti-PF4 antibodies is a bit misleading here: he was negative at baseline, positive post-vaccination according to the presentation)
Helpful timeline here:
Read 36 tweets
14 Apr
Denmark just announced they will not restart vaccinations with AstraZeneca’s #covid19 shots and instead rely on the other vaccines.

“Danish-Norwegian registry studies have revealed a higher than expected frequency in the number of specific side effects”

sst.dk/en/english/new…
As I have said before these decisions depend a lot on context. In this case:
- infections are low
- other vaccines available and
- oldest people largely vaccinated (so future vaccinees would be younger)

Different places will come to different conclusions and that’s reasonable.
"In the midst of an epidemic, it has been a difficult decision to continue our vaccination programme without an effective and readily available vaccine against COVID-19. However, we have other vaccines at our disposal, and the epidemic is currently under control.”
Read 4 tweets
13 Apr
“While these events are very rare, we’re recommending a pause in the use of the J&J #COVID19 vaccine in order to prepare the healthcare system to recognize and treat patients appropriately and to report severe events they may be seeing in people”, says @CDCgov’s Anne Schuchat.
@CDCgov Q how long the pause may be
“The timeframe will depend obviously on what we learn in the next few days. However, we expect it to be a matter of days for this pause”, says @DrWoodcockFDA.
@CDCgov @DrWoodcockFDA "The issue here with these types of blood clots, is that if one administers the standard treatments that we as doctors have learned to give for blood clots, one can actually cause tremendous harm or the outcome can be fatal”, says Peter Marks.
Read 9 tweets
13 Apr
I just don’t get it, @NateSilver538. I admire your work on polling and you clearly appreciate the complexity there.
You can argue about the FDA decision for sure, but pretending it is blindingly obvious that they are wrong, simply isn’t true or fair to this situation.
As so often in this pandemic, I agree with @angie_rasmussen here.
I don’t think vaccinated individuals need to lose sleep over this, but I certainly want people at the agency tasked with ensuring the safety of vaccines to lose a little sleep over this.
Another good voice of reason when it comes to vaccines is @nataliexdean
Read 4 tweets
13 Apr
US FDA is recommending a pause in the use of the J&J #covid19 vaccine while they investigate 6 reported cases of the kind of rare clotting disorder seen after AZ vaccine too.
Should not come as a huge surprise to those of you who have been following the reporting on this.
As @GretchenVogel1 and I wrote last week, EMA is already investigating this safety signal.
Given that this vaccine (like AZ one) too uses an adenovirus to deliver the genetic instructions for #SARSCoV2 spike protein, there were worries about this.

sciencemag.org/news/2021/04/h…
@GretchenVogel1 There will be a press conference at 10am ET that may have more information.
But for now, think of this as a cautious approach to a safety signal, similar to what, for instance, PEI in Germany did when reports of AZ side effects emerged almost exactly a month ago.
Read 4 tweets

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