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From the Daily Telegraph
AstraZeneca vaccine may increase risk of serious neurological condition
Scientists believe the jab’s Trojan horse delivery system could be causing a rise in Guillain-Barré syndrome cases
BySarah Knapton, SCIENCE EDITOR28 May 2022 • 5:26pm
The AstraZeneca vaccine may increase the risk of the serious neurological condition Guillain-Barré syndrome (GBS) with the jab’s Trojan horse delivery system possibly to blame, scientists believe, in a discovery which may apply to similar vaccines.
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Like many vaccines, the Oxford jab uses a weakened chimp adenovirus to deliver the coronavirus spike protein into the body, and scientists have speculated that a reaction to adenovirus may be responsible for the rise in cases.
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"'The EMA and other international bodies including the WHO, have all stated that the benefits of vaccination continue to outweigh any potential risks.”
The speculated mechanism proposed by Professor Michael Lunn is nonsense, it is not "molecular mimcry". In fact several studies (and most likely the vaccine manufacturers themselves) have already compared the genetic sequences and found there are no matching sequences of sufficient length. Secondly, GBS is mediated in a majority of cases by antibodies against gangliosides or ganglioside complexes, which are glycolypids not peptides.
The most likely mechanism that explains all of the possible triggers of GBS is B-cell cocapture (Campylobacter Jejuni is a special case). Both the SARS-CoV-2 spike protein and the adenovirus capsid have been shown to bind to gangliosides (through sialic acid binding). The key point is the B-cell is autoreactive to self components (the gangliosides), but presents non-self peptides on MHC receptors to T-cells. (Also notably glycolipids aren't presented on MHC, there is a separate mechanism (CD1))
But one of the risk factors of the AZ vaccine (also for the thrombosis and thrombocytopenia syndromes) is the fact that the vector is more stable (than mRNA vaccines) and therefore is able to circulate to tissue other than the lymph near the muscle, which can hypothetically increase the risk of the B-cell cocapture process occurring.
The other factor when considering excess cases in whole populations is the underlying virus itself can trigger GBS, so if a vaccine has lower efficacy at preventing infections (compared to an alternative vaccine), it's also less likely to prevent GBS cases due to the virus itself.