Digging into the detailed EMA report on the AZ vaccine investigation. (The committee vote for their decision was 31 out of 32.) They discuss several hypotheses that have been proposed for the phenomenon, if it's triggered by the vaccine.
ema.europa.eu/en/documents/p…
...1/n
ema.europa.eu/en/documents/p…
...1/n
..1st was one from researchers in Germany/Austria, based on studying several of the people: that it's similar to heparin-induced thrombocytopenia ("HITT-like"), & related to Platelet Factor 4. assets.researchsquare.com/files/rs-36235… (preprint)...2/n
...EMA conclusion: there are similarities, so still needs to be investigated. But there are differences too: eg HITT doesn't cause a condition that occurred here (DIC). So they called this unproven...3/n
...Next one: could it be unrecognized Covid-19, as coagulation problems are a feature of the disease? Their conclusion: still to be investigated, but too many people tested negative for the disease - & it wouldn't explain why it was happening with 1 vax & not the others...
..Another. Could it be because the AZ vax codes not just for the virus' protein, incl a tPA to increase immunogenicity? But they knew of no evidence it could, eg, interfere with platelets. They don't expect the issue is not using the same protein sequence other vaxes use ...5/n
...Another hypothesis: could it be the SARS-CoV-2 spike protein immunogen encoded in the AZ vaccine? They considered this unlikely, because it wouldn't explain why it wasn't occurring as often with other vaccines that use very similar immunogens...6/n
...Another: could it be impurities or other components of the vaccine? They didn't think this could explain it. If it was impurities, it would have been related to specific batches & it isn't. They don't suspect any of the other components ...7/n
...Could it be caused by the chimpanzee adenovirus vector? One of the EU countries thinks it's likely, but though the committee agreed it's plausible, they think it's more likely the cause is some kind of link with Covid-19 specifically, not the adenovirus...8/n
...So. No answer here. Just a mystery that needs to be solved. And a very long to do list for investigators. /9
...aaaand PS: Several tweets asking, do they think it's because the AZ vaccine doesn't use the 2P protein that the mRNA vaxes, J&J, & Novavax use? That's in the 5th tweet in this thread: this group didn't suspect that's why. Here's that conclusion. 10/10 
...2nd PS: I hadn't read the report before - turns out it's not a new one from today. (Thanks, @irishinneburg!) The hypotheses gel with what they said at the press conference though.
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