Experts report impurities in the Astrazeneca vaccine - this could be the main reason behind side effects such as Blood Clots

Researchers claim that this contamination could influence the vaccine effect and possibly also promote side effects such as Cerebral venous sinus thrombosis (CVST) also known as a blood clot.

The results of the study say that the batches examined contained larger proportions of human and viral proteins that are not part of the vaccine.

Among the vaccines against the coronavirus, the vaccine from AstraZeneca has already been negatively noticed several times: in the approval, there were ambiguities in the dosage and the effectiveness was in some cases significantly lower than with the mRNA vaccines.

Researchers at the University of Ulm say they have found contaminants in AstraZeneca’s Covid vaccine. The batches studied contained larger proportions of human and viral proteins that are not part of the vaccine. It is conceivable that these contaminations affect the vaccination effect and may also promote side effects such as sinus vein thrombosis.

In addition, the vector vaccine based on a chimpanzee adenovirus appears to promote Cerebral venous sinus thrombosis (CVST) a rare but potentially dangerous side effect. These are likely triggered by an autoimmune reaction induced by the vaccine.

Excess proteins in the vaccine

In search of a possible trigger for this side effect, Lea Krutzke and her colleagues from the University of Ulm examined samples from three batches of the AstraZeneca vaccine in more detail for their ingredients. To do this, they first compared the protein bands of the vaccine samples, which were made visible by means of silver staining and gel electrophoresis, with those of their own, purified adenovirus vector.

The results showed that the band pattern in the protein gel differed significantly in the two samples: Compared to the own adenovirus vector, the AstraZeneca samples showed significantly more protein bands that could not be explained by the adenoviral vaccine, according to team leader Stefan Kochanek.

A mass determination of the protein content also produced a similar result: Instead of the theoretically expected 12.5 micrograms, the AstraZeneca samples contained up to 32 micrograms of protein.

The AstraZeneca vaccine contained significantly more proteins than would be expected from the carrier virus and known additives alone.

But what proteins are these?

To find out, the research team carried out further analyses using mass spectrometry, among other things. It turned out that the vaccine contains more than 1,000 proteins and protein fragments, most of which have nothing to do with it. Depending on the batch, one-third to half of these proteins were viral, but up to two-thirds came from human cells.

As the researchers explain, the excess viral proteins are likely to come from precursors of adenoviruses, which arise when vector viruses multiply in cell cultures. These include, for example, incompletely assembled capsids, the protein shells that surround the adenovirus’s genetic material.

Heat shock proteins with potentially immunological effects

Among the human proteins in the vaccine, the team identified various fragments of cell components that come from the nucleus, the Golgi apparatus or the cell skeleton. So-called heat shock proteins and chaperones were particularly common. Both serve, among other things, to help other proteins to fold correctly and are mainly formed during cell stress.

“The majority of proteins found should not have a negative impact on vaccines,” Kochanek explains. “However, extracellular heat shock proteins are known to modulate congenital and acquired immune responses and enhance existing inflammatory responses. They have also been associated with autoimmune reactions.”

“The majority of the proteins found are unlikely to have any negative effects on vaccine,” explains Kochanek.

“However, extracellular heat shock proteins are known to modulate innate and acquired immune responses and to intensify existing inflammatory reactions. They have also been linked to autoimmune reactions.”

Contamination to blame for vaccination side effects?

According to the researchers, it cannot be ruled out that the protein contamination of the AstraZenecva vaccine may have undesirable effects: “The intramuscular injection of proteins that are not part of the active principle of action of the vaccine can produce effects on various levels,” said the team.

“Some of these proteins could be more than just inactive followers.”

The excess viral proteins could reduce the quality of the desired immune response and thus reduce the effectiveness of the vaccination.

Some other proteins may exacerbate the side effects of vaccination: “We believe it is likely that the protein impurities documented here are involved in the strong clinical responses with flu-like symptoms that are often observed one to two days after vaccination,” Krutzke and her colleagues write.

In addition, it cannot be ruled out that some of the heat shock proteins could promote the autoimmune reaction responsible for a blood clot.

Revise manufacturing and quality control

According to the researchers, the contamination of the AstraZeneca vaccine urgently needs further clarification.

“The large number of impurities found, at least some of which could have negative effects, makes it necessary to revise the manufacturing process and quality control of the vaccine,” Kochanek emphasizes.

“This could potentially increase the effectiveness of the vaccine in addition to security.”

As the team explains, the removal of all protein residues of the cell culture used for virus cultivation is usually an important quality standard. In the case of the AstraZeneca vaccine, however, these proteins appear to be difficult to detect in the tests used for verification.

This is why improvements must now be made, Kochanek and his colleagues concluded.

Source: Ulm University

Image Credit: iStock

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