Parts of the coronavirus protein carried by adenovirus vaccines and expelled from the nucleus of the target cell could be the cause of cases of thrombosis.
- Adenovirus vaccines against Covid-19 have caused very rare cases of sometimes fatal thrombosis
- German scientists offer an explanation that would be linked to the particularities of adenovirus vaccines
It will have sufficed with 309 cases: the thromboses suffered by very few people among the 33 million vaccinated in Great Britain with products from AstraZeneca and Janssen sowed the start of panic and seriously disrupted the vaccination campaigns organized in the around the world to fight the Covid-19 epidemic.
In the journal Research Square and through an article that has yet to be validated by their peers, German scientists provide their explanation for these “undesirable” effects which have cast doubt on the safety of the two adenovirus vaccines: when the genes of the virus integrate the nucleus of the cells which trigger the immune reaction, the protein of SARS-CoV-2 carried by the adenovirus vectors would separate into several parts and it is these protein parts, expelled from the target cell, which would cause thrombosis.
An effect specific to adenovirus vaccines
This is the reason why severe vaccine reactions have only occurred with AstraZeneca and Janssen vaccines which are adenovirus vaccines. The other products used in vaccination campaigns, those from Pfizer and Moderna, work from a different process: messenger RNA carries the genetic material of the virus into the cell but never enters the nucleus.
So much for the explanation. And German scientists are also advancing the solution. They suggest that altering the sequence of the gene encoding the spike protein to prevent it from splitting into multiple parts would remove the risk of thrombosis.
It is a hypothesis which, if it needs to be validated and confirmed by other scientists, at least advances the subject since until now, apart from possible errors made at the time of the injection which would have caused the vaccine directly in the blood vessels, nothing, allowed to explain the cases of thrombosis of which 56 had fatal consequences in Great Britain.
The French no longer trust
It will probably take more certainty about the real causes of the problem before confidence in the two adenovirus vaccines affected by adverse effects returns to the general public. In France, while 100,000 primary injections with AstraZeneca took place every day until mid-March, there are currently only barely 10,000. The consequence being in particular that 3 million doses of this vaccine would currently be stored in France. This product can no longer be used for those under 55, although the campaign is now open to all adults. And the youngest among those who received a first injection with an adenovirus product must, for the second dose, receive a messenger RNA vaccine.
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