Although uncommon, vaccine-induced immune thrombotic thrombocytopenia (VITT) is much more serious than a typical blood clot because it causes cerebral venous sinus thrombosis (CVST), blocking the veins that drain blood from the brain and May cause fatal bleeding.

German researchers believe that the problem lies in these two vaccine-like delivery systems. Both vaccines use adenoviral vector technology to send genetic instructions to cells to produce coronavirus spike proteins.

The findings were published online on Wednesday and have not yet been peer reviewed. Please note that this type of vaccine sends the DNA gene sequence of the spike protein directly into the nucleus. At this time, some parts of the spike protein DNA may become spliced ??or broken.

The research is based on the team’s own laboratory work, which involves experiments on the commonly used HeLa human cell line, showing that these “bad” breakdowns can cause mutations in the spike protein DNA, which may make these proteins more difficult to interact with. The protein binds to the cell, causing it to be secreted into the body, and may trigger an “inflammatory response”, leading to rare blood clots.

Researchers suspect that three steps are being taken: useless spike proteins that flow through the blood, combined with new antibodies designed to attack them, plus the highly specific blood flow conditions in the veins draining from the brain, “maybe Caused a rare situation. But serious incidents occurred after the vaccination.” The research team wrote.

Public Health Agency of Canada (PHAC) It is now estimated that the incidence of VITT in Canadians receiving the AstraZeneca vaccine is between 1 in 83,000 and 1 in 55,000, with a mortality rate of 20% to 50%, but as more data becomes available, this number may occur Variety.

PHAC said in a statement issued to CBC News on Thursday that so far, Canada has administered 2 million doses, including 27 confirmed VITT cases and 5 deaths.

The “missing” problem in mRNA vaccines

The researchers said that their study provided “the first molecular evidence” that adenoviral vector-based vaccines encoding spike proteins “exhibit problems that are completely absent in mRNA-based vaccines,” such as Pfizer-BioNTech and Moderna.

The lead author of the study, Professor Rolf Marschalek, Professor of Pharmaceutical Biology at Goethe University in Frankfurt, said: “The adenovirus vaccine is delivering its complete DNA (including antigen genes) to the nucleus where transcription occurs.” In an email to CBC News Say. “Transcription refers to the copying of RNA from DNA.”

Marschalek says that the RNA is then spliced ??into fragments, which encode smaller protein variants as they diffuse from the nucleus to the cytoplasm. He said that his team has identified “joint products” with “relevant quantities” in experiments, so they are of great significance.

If proved to be correct, then this discovery may lead to the future reformulation of AstraZeneca-Oxford vaccine and Johnson & Johnson vaccine to prevent rare blood clots.

The researchers said that they strongly recommend that the adenovirus vector vaccine should be “re-optimized” to avoid “accidental splicing reactions” and “increase injection safety.”

Marschalek told CBC News: “When we know exactly where all these splicing reactions occur, we can modify the gene appropriately to make it’splicing safe’.”

The researchers said that the reason why mRNA vaccines such as Pfizer-BioNTech and Moderna do not have similar problems in splicing and blood clotting is because the spike protein mRNA instructions they provide cannot enter the nucleus.

Experts say the data is “simplified” and more research is needed

However, due to the lack of specific causal data, external experts urged caution. They said that it is too early to draw definitive conclusions on the theory.

“The authors show convincingly that compared to mRNA vaccines, there may be some differences in the processing methods of spiked proteins when delivered through these viral vector vaccines, but they do not directly or clearly indicate that this difference is responsible for this situation. The reason for these thrombotic events,” said Matthew Miller, associate professor of infectious diseases and immunology at McMaster University in Hamilton.

Professor Alyson Kelvin, an assistant professor at Dalhousie University and a virologist at the Canadian Vaccines and Vaccines and Infectious Diseases Organization in Saskatoon, was also very cautious in evaluating this finding. She said the data supporting it was “very thin.”

In an email to CBC News, she said: “I haven’t seen much mechanical data showing a causal relationship between splice variants and blood clots.”

“I think this is an interesting discovery that should be explored, but there is nothing left to hang at the moment.”

Watch | Canadian experts launch new German vaccine and blood clot research:

Matthew Miller, associate professor of infectious diseases and immunology at McMaster University in Hamilton, helped launch a new German study that provided a possible solution to the rare and severe blood clotting condition after a vaccine, but he emphasized that there is no Causal evidence supports the team’s findings. 2:06

Dr. Zain Chagla, an infectious disease expert at the Hamilton St. Joseph Health Center, agrees that more research is needed, noting that the theory cannot explain the key feature of VITT: low platelet content, small blood cell fragments that help the treatment form clots to stop bleeding.

Chagla told CBC News: “This may be all herring…or at least not a smoker.”

The researchers themselves and other external experts emphasized that the findings did not answer many key questions about how this rare coagulation condition occurs, including why the coagulation appears to occur in the channels that drain blood from the brain and surrounding areas, and Why it only affects some people, but not most people.

Filming was suspended due to blood clot concerns

This study was conducted after an earlier study conducted in Norway in March, which identified the mechanism behind VITT and pointed out that it was due to “Strong immune response“The AstraZeneca vaccine was filmed.

This discovery has had a major impact on the promotion of the vaccine in Canada and around the world, resulting in the suspension of the vaccine’s use in parts of Europe.

Canadian Vaccine Advisory Council Recommended AstraZeneca vaccine for Canadians over 65 Then on March 16 It is recommended to suspend immediately After reports of VITT in Europe, it was used in Canadians under 55 in late March.

Currently using AstraZeneca vaccine Approved by Health Canada Applicable to Canadians 18 years and older, although most provinces have Stop giving the first dose And reserve the second supply in the future.

Watch | Questions revolve around the next development of AstraZeneca vaccine:

More and more provinces are restricting the first dose of the AstraZeneca-Oxford COVID-19 vaccine, which raises questions about the vaccine that is still available and people who have already received it. 3:38

Johnson & Johnson vaccine is Recommended for all Canadians over 30, But the Canadian vaccination consultant also said that when deciding whether to keep another vaccine, it is necessary to weigh the risks of VITT and COVID-19 levels in the community.

Health Canada is now Delay the distribution of the first batch of vaccines It became clear that the dose that arrived last month was processed in the same American factory that was caught in quality control issues.

According to Miller, if the latest theory behind VITT is confirmed and these vaccines can eventually be used to prevent rare but potentially fatal blood clotting, it will be good news for Canada and the global community.

He said: “Due to limited supply and strong global demand, we are already experiencing and observing huge inequalities in the global vaccine distribution.”

“So, ideally, we want as many safe vaccines as possible to be used by the global population that needs management.”

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