Shots using viral vector technology haven’t been administered at scale

Saturday, May 15th, 2021

In Germany, one researcher thinks he has found what is triggering the clots in patients who have received a COVID vaccine:

Andreas Greinacher, a blood expert, and his team at the University of Greifswald believe so-called viral vector vaccines — which use modified harmless cold viruses, known as adenoviruses, to convey genetic material into vaccine recipients to fight the coronavirus — could cause an autoimmune response that leads to blood clots. According to Prof. Greinacher, that reaction could be tied to stray proteins and a preservative he has found in the AstraZeneca vaccine.

Prof. Greinacher and his team has just begun examining Johnson & Johnson’s vaccine but has identified more than 1,000 proteins in AstraZeneca’s vaccine derived from human cells, as well as a preservative known as ethylenediaminetetraacetic acid, or EDTA. Their hypothesis is that EDTA, which is common to drugs and other products, helps those proteins stray into the bloodstream, where they bind to a blood component called platelet factor 4, or PF4, forming complexes that activate the production of antibodies.

The inflammation caused by the vaccines, combined with the PF4 complexes, could trick the immune system into believing the body had been infected by bacteria, triggering an archaic defense mechanism that then runs out of control and causes clotting and bleeding.


One reason vaccine-induced clotting might not have been reported in the past is because shots using viral vector technology haven’t been administered at scale. The Russian vaccine Sputnik V and the shot by CanSino Biologics from China use the same technology as AstraZeneca and Johnson & Johnson, but haven’t been linked to the condition so far.

The only similar shot widely administered before the pandemic is one against Ebola by Johnson & Johnson, which was given to at least 60,000 people as of last July.

Clotting occurs between one in 28,000 and one in 100,000, according to European data — extremely rare amid the hundreds of millions of doses administered so far, yet higher than one in 150,000 previously assumed by some medical authorities, Prof. Greinacher said. Most of the hundreds of people who have been diagnosed recover, but between a fifth and a third have died, and others could suffer permanent consequences.

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