Let’s start with what doctors have actually observed in some AZ vaccinees:
This is not about your garden-variety thromboses. It’s wide-spread clotting with rare thromboses like cerebral venous thromboses coupled with a low platelet count, a very unusual picture.
Most hematologists will immediately think of disseminated intravascular coagulation DIC (“Verbrauchskoagulopathie” for Germans). That is usually seen in patients with sepsis or severe trauma or sometimes cancer patients. But none of that is the case here.
That is why doctors started thinking about HIT (heparin-induced thrombocytopenia) which can have a similar clinical picture. It happens in rare cases when patients are given the blood thinner heparin.
...
Greinacher and other scientists think that something similar may be happening here - only without heparin.
The mechanism is still unclear but the researchers we talked to all agreed that the symptoms were so particular that it looked like something real caused by the vaccine.
1. Norway has vaccinated 130,000 people with AZ and they have seen five such cases, three of whom died.
That's a lot, about one case in 25,000 vaccinees. As
@SaraWatle
told me, that’s "a high number with a very critical outcome in previously healthy, young individuals”.
2. Germany has vaccinated roughly 2,1 million people with AZ.
@PEI_Germany
told me that until noon Thursday, 21 cerebral venous thromboses had been reported, incl. 7 deaths.
In 12 cases thrombocytopenia was also reported (it’s not clear for the other cases).
3. Then there is the UK, which has given more than 10 million doses of AZ and has reported only 5 such cases. Did they miss cases because they were vaccinating elderly people first? Is something else going on? That will be on thread to follow in next weeks.
And what about use of the vaccine?
Some context first:
It’s never just about risks, but the balance of risk and benefit. We know some vaccines have serious, rare side effects like the yellow fever vaccine for instance. We still use them because the benefits outweigh the risks.
But with #covid19 the risk of dying is very different for a 75 year old and a 25 year old. And so some countries like France and Finland have made what seems a reasonable choice:
use the AZ vaccine only in the elderly where benefit most clearly outweighs risk.