Confirmed: There is a blood clot problem with the AstraZeneca vaccine
UPDATE: May 15, 2021
It's been confirmed for some time now that there is in fact a problem with the AstraZeneca vaccine and several countries have already stopped using it. More data continues to trickle in though and now other countries have restricted or dropped its use altogether.
Canada is the latest country to announce plans to phase out use of the AstraZeneca vaccine. They had previously limited its use to those over a certain age. Then there was some confusion as some provinces and leaders said that they'd still give a second dose of AstraZeneca to those who'd already had their first dose of it, before even that was dropped and plans announced to stop administering it altogether.
Canada found one of the highest rates yet of the deadly blood-clotting known as vaccine-induced immune thrombotic thrombocytopenia (VITT) in its population that had received the AstraZeneca vaccine — 1 in 55,000 cases per dose — which may have spooked the government. An earlier study out of the UK had found a much lower rate of 1 in 250,000.
More recent data though has found the side effect to have occurred at a rate of ~1 in 111,000 in the UK, with 41 total deaths. In Germany, the data of which we got earlier on, they found a rate of ~1 in 87,000 (2.7 million doses and 31 cases), including 9 deaths.
Early on it had been speculated that the cases of blood clots may be no more than what would be expected to occur naturally in a population of the size that received the vaccinations but it's clear now that the relationship between the vaccine and the side effect is causal, and given that it affects young women most, a relatively low-risk demographic for covid, it puts into question its use.
Previous reports of blood clots in those who'd had the AstraZeneca vaccine were explained as possibly being what you'd expect to see naturally in a population as large as the tens of millions of people that received the vaccine, but this report from Germany puts that in doubt.
This is said to be a rare blood clot condition but the data isn't showing that. A quick calculation shows that for 2.7 million doses of the AstraZeneca vaccine administered in Germany at the time the report was written, the 31 cases and 9 deaths make for 1 in ~87,000 odds of getting this severe blood clot disorder and 1 in ~300,000 odds of dying.
All but two cases occurred in women aged 20 to 63 too (it's unclear if the other two were just men or men outside that age range as well), many of which may have been at relatively low risk from the covid virus itself — something with implications for the interest young people would have in getting the AstraZeneca vaccine.
NOTE: Vaccines are of course critical public health tools in eradicating diseases and should be highly useful in ending the coronavirus pandemic. The Pfizer and Moderna vaccines in particular have been highly effective and there are no reports of similar possible side effects in them (they use a different method). Tens of millions of people have received the AstraZeneca vaccine in other countries too and it's possible that the problem is unique to Germany.
Revisions:
Rewrote parts to improve the writing. No changes to the data or points made. Aug 2, 2023
Broken link updated. Jun 5, 2023
Fixed some spelling mistakes, removed an opinion from the note at the bottom. Apr 5, 2023
