Comment by textman | Hacker News Reader

Comment by textman | Hacker News Reader

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"The incidence of cerebral venous thrombosis (CVT) varies between studies, but it is estimated to be between 2 and 5 per million per year. A recent study in the Netherlands with comprehensive ascertainment suggested a much higher incidence." https://www.ahajournals.org/doi/full/10.1161/STROKEAHA.116.0...

So the six reported cases in 6.8 million vaccinations seems low. Glad I read about all this because I got the J&J vaccine 12 days ago. No noticeable side effects so far. I exercise a lot and did a 5 mile hike four days ago that resulted in a slightly strained a calf muscle. I have been taking it easy the past few days, meaning sitting and reading a lot more than usual. So after learning about the blood clotting, have started exercising the legs frequently. My optimistic thinking is that even if the vaccine does cause an increased risk of CVST that risk can be eliminated via exercise.

It will be most interesting to learn if those six cases involved people at high risk, if they exercise regularly, etc.

If you’re doing the calf exercises to ward off a DVT, (and not to just stretch your strained calf!) you may be barking up the wrong tree.

The preliminary theories (backed by the thrombocytopaenia) are that, if there’s a vaccine induced thrombosis with thrombocytopenia, it is probably immune-mediated (similar to HITT - heparin induced thrombocytopenia and thrombosis).

And then there’s some weird thing that makes them form in your venous sinus.

But there were also reports of more typical blood clots (ie DVTs), the first European Medicines Agency advisory (0) said that this was within the level of noise (im now talking AstraZeneca, so apologies for shifting vaccine as generally they should be considered separately until the evidence catches up, although everyone is quickly drawing parallels between them)

(0) https://www.ema.europa.eu/en/news/covid-19-vaccine-astrazene...

Ps apologies for not referencing around HITTs and theories around antibody-mediation for CVT. Basically it’s all pretty noisy anyway at the moment and so my here-say from the medical tea rooms is as good a gossip as any, as long as everyone is aware that no one really has any definitive idea what may be going on yet

Agreed, I don't think anyone knows clearly what is happening. Some additional points that are related.

Thrombocytopenia has been a known complication of adenovirus vectors that researchers have worked to overcome in recent decades.

These incidents mirror HITT (women are at higher risk for HITT) and seem to be happening in the timeperiod where IgG titers spike post vaccination.

To me this indicates it's not unlikely something with the adenovirus vectored vaccines (J&J, AZ) is causing this issue. And because this thread seems to have gone to hell, I'll add that I support doing subgroup specific risk calculations and allowing vaccinations to proceed where it makes sense.

https://jvi.asm.org/content/81/9/4866 https://ashpublications.org/blood/article/109/7/2832/125650/... https://pubmed.ncbi.nlm.nih.gov/17148587/

Just want to add that this is not a new theory and has been circulating in medical circles for roughly a month [1]. There is also the hope that when it happens it can be diagnosed and treated.

[1] https://twitter.com/LJohnsdorf/status/1371721321336475651 (in German)

Good take.

Arterial clots with thrombocytopenia is incredibly rare. Additionally the PF4 activity in these patients is very abnormal and appears to be to immune mediated. Lots of science and focus going into the mechanism around this now. The other recent NEJM articles around clots associated with the other adenovirus COVID vaccines are likely a similar phenomena.

2-5 per m per y is an incidence over the entire year. Assuming a uniform distribution over the 365 days, then the probability of getting it "on that day" becomes a probability of 1-2 per billion.

So the reported cases of are not comparable. They are really, really high.

And while I agree about the relative risk vs covid, again this is not a fair comparison. For many people who are isolating, then a person never leaving the house has a very low risk from covid, both personally and transmitting it. You are not asking people to exchange a very small risk from the vaccine vs a very high risk from covid. You are asking them to exchange a very small but roulette-like risk from the vaccine, versus a presumably equally small if not smaller risk from covid due to their circumstances.

Note, what I am "not" saying is that peoples shouldn't be vaccinated. I'm just saying artificially trivialising the risk further using bad math isn't doing anyone any favours.

"So the six reported cases in 6.8 million vaccinations seems low."

No, because those 6 cases are something more like "1 per day" rather than "per year". Or maybe "per week". But either way, you need to multiply the "per year" base rate by a large number to get the base rate for "coincidentally happened immediately after a particular event", for some definition of "immediately".

It's reports within 3 weeks, so something like 18 per million per year.. The larger danger is any interaction with an automobile to get to the appointment.

They also appear to cluster in young women and one young man (from the phase 3), do it’s quite probable that the “6 million” is not representative.

Using 1 per year is useless unless it's adjusted to a ratiometric form like percentage or per capita

My wife says this is not about exercise, while living a healthy lifestyle is good, apparently this specific condition causes clots to form in the brain itself as a result of low platelets.

CVST with Thrombocytopenia is the name.

Similar to AZ, all six were women between the ages of 18 and 48.

20% male (1 patient) in this report https://www.nejm.org/doi/full/10.1056/NEJMoa2104882

I think with numbers that small it’s hard to tell if it hat 1 male is purely a coincidence or not. Also I don’t know if percentages are useful either.

seems like they were all young women. so let’s say young women make up 1/4 of those vaccinated.

for them it’s more like 1/250k

That’s what I keep saying! People are saying it’s 1 in a million chance, but unless all the people who got the vaccine were women than it’s not. The instance could be far higher but it’s not possible to know without knowing how many were given to men vs women

But not _young_ women. We may be seeing something legitimate.

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