The AstraZeneca vaccine (AZ vaccine for short), jointly developed by Oxford University in the UK and AstraZeneca Pharmaceuticals, causes rare blood clots as a side effect and can even be fatal. This not only shocked the medical and political communities, but also caused several countries to offer countermeasures to restrict the use of the vaccine, and Denmark even announced to stop using AZ vaccine completely.
So why does the AZ vaccine cause rare thrombotic side effects, and is there any solution? German researchers have managed to unravel part of the mystery.
Professor Andreas Greinacher, M.D., of the University of Greifswald, Germany, studied blood samples from affected individuals and found that “in rare cases antibodies formed after AZ vaccination” activated platelets, which then acted like a healing wound, triggering a blood clot. The platelets then acted like healing wounds, triggering blood clots in the brain.
Professor Greinercher then developed a treatment with other European scientists and the Paul Ehrlich Institute, which is in charge of vaccines. Professor Greinercher said, “If cerebral vein thrombosis occurs in the future, we will be able to treat it successfully.”
The mysterious antibody
Professor Greinercher, who is director of the Institute of Immunology and Transfusion Medicine at the University Medical Center Greifswald, has studied seven affected people with other transfusion doctors to understand how the clots form.
“Exactly what triggers the formation of the specific antibodies is not yet clear and we are continuing our research.” Professor Greinercher explained that usually after vaccination, antibodies are initially formed in the body, and in rare cases this leads to the formation of specific antibodies that bind to and activate platelets.
According to the report, the task of platelets is to close blood vessel damage during the wound healing process in order to stop bleeding. If these platelets are activated without a bleeding condition, they can form clots in the blood and block blood vessels.
Testing and Treatment
In order to detect “the presence of these specific antibodies in the blood”, researchers have developed a test procedure. The test can be used if symptoms of blood clots, such as leg pain or unusually severe headaches, occur after vaccination.
However, one must distinguish the immune response one to two days after vaccination from the complications that usually appear only four days after vaccination. Therefore, Professor Greinercher recommends that one should see a doctor immediately “if symptoms persist after three days, or if they reappear after a short break.
To treat this rare side effect, medical doctors plan to use an intravenous immunoglobulin (ivIgG) to block platelets and thus inhibit this mechanism. The clot itself can then be dissolved by anticoagulant drugs.
Facts and figures
Other vaccines have side effects, some of which are serious and even fatal. In particular, the widely used Pfizer-BioNTech vaccine appears to be more deadly than the AZ vaccine in some cases. However, the Pfizer-BioNTech vaccine tends to pose a risk only to older people, with data showing that those at risk range from 68 to 81 years old, while the AZ vaccine is age-neutral, with risks occurring in people from 22 to 63 years old.
According to the European Medicines Agency (EMA), as of April 2, a total of 407 people (24 to 102 years old) died in Germany as a result of vaccination against the CCA virus (Wuhan pneumonia). The time to fatal reaction of the deceased ranged from 1 hour to 40 days. Of these, 321 died after receiving the Pfizer-BioNTech vaccine; 19 died after receiving the AZ vaccine; 7 died after receiving the Moderna vaccine; and 60 were unsure which vaccine they had received.
Germany has announced that people under the age of 60 who have received the first dose of AZ vaccine will have their second dose switched to a different brand of vaccine, possibly Pfizer-BioNTech or Moderna. Whereas in Germany it was initially recommended that people over the age of 65 not receive the AZ vaccine, the current policy amounts to a major reversal, with the AZ vaccine being given only to people over the age of 60. The EU Medicines Agency, on the other hand, continues to emphasize that the benefits of AZ vaccination outweigh the drawbacks.
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