"Confirmed", no. Suspected, there is possibly a correlation (which is different than causation) between AZ & CVST, it may cause a very rare auto-immune reaction for those under 55, especially women.
To put it in perspective, the odds of someone from the 45-54 age cohort *dying* of COVID is roughly 1.4%. (number from https://www.vox.com/2020/3/23/21190033/coronavirus-covid-19-deaths-by-age). Let's me super-conversative and round that down to 1%.
1 person out of every 100 who gets sick from that age cohort will probably die (note: between 55 & 65, the risk about doubles).
For CVST, there has been 12 reported cases out of 20,000,000 vaccinated people (about 1/3 of the population) in the UK (note: not all of them died). (see https://www.ema.europa.eu/en/news/covid-19-vaccine-astrazeneca-benefits-still-outweigh-risks-despite-possible-link-rare-blood-clots)
That's a 0.00009% chance globally of developing CVST from the vaccine, assuming the vaccine is the cause. I couldn't find breakdowns as to how many from the 45-55 cohort specifically have been vaccinated, but there's 4.66 million people that age in UK generally, and they're currently booking appointments for those in the low 50's. (https://www.bbc.com/news/health-55274833). So let's make a guess and say 1.5 million people from that cohort have been vaccinated already. In that cases, there's a whopping 0.0008% chance of developing CVST.
You see where this is going, right? The chances of dying from Covid is roughly 1,250x greater than the unlikely event of developing CVST. In the UK, the death rate for under-65's has roughly halved since vaccination started (see BBC article above), so considering that the same vaccine that has a 0.0008% chance of perhaps giving you CVST will actually lower your chances of dying from 1 in 100 to 1 in 200...
The benefits clearly outweigh any risks at this point. You're probably just as likely dying in a collision on your way to a vaccine appointment than developing CVST.
Edit: I take back my comment about collisions. I calculated that there's, on average, 2,103,049 km traveled per serious traffic injury in MB, so statistically it's unlikely. But you see my point? You probably engage in things that are far riskier (or just as risky) than the AZ vaccine every day without even thinking about it. No activity or medical treatment is riskless, but you need to keep perspective on absolute vs. relative risk, and the potential rewards.
Edited by Abbysmum, 2021-03-24 11:01:57