Thrombosis after vaccination: cause decoded – medical practice

How a faulty immune response can cause thrombosis

Due to certain vaccination there is minimal risk of developing thrombosis with adenovirus-based vaccines. According to German Heart Foundation such complications occur one to two people per 100,000 vaccinated on. The German research team is currently investigating how Thrombosis occurs after vaccination be able.

Working Group of the Clinic and Polyclinic I: Cardiology at the LMU Clinic in Munich Dr. Leo Nicolai The study examines how Thrombosis occurs in rare cases after vaccination with adenovirus-based vaccines be able. The team now reports on the findings so far in the professional magazine “Blood”.

Thrombosis during vaccination against COVID-19

As part of the vaccination against COVID-19 vaccine Vaxzevria from AstraZeneca and vaccine from Johnson & Johnson Very rarely, vaccination complications in the form of thrombosis have occurred after vaccination, and the cerebral veins have often been affected. Among other things, for this reason have not used these vaccines in Germany since December 2021.

“For the development of future vaccines and the safety of people with a susceptibility to thrombosis, including patients with cardiovascular disease, it is important to understand the causes and mechanisms of these rare thromboses as a deluded immune response – here in the context of vaccination. “.he explained Professor Dr. Thomas Voigtlander. He is the chairman of the board of the German Heart Foundation.

“It is important to emphasize that in terms of protection against the consequences of Covid-19 infection, the advantage is still clearly on the side of vaccination against Covid – although in rare cases there are sometimes serious side effects with mRNA- or vector vaccine against Covid “emphasizes the cardiologist Voigtländer.

What does VITT mean?

Vaccination-induced blood clot in atypical places like the brain veins they are in medical jargon with the acronym WHITE indicates what “Vaccine-induced immunothrombotic thrombocytopenia“It stands. That means one immune system malpractice.

Platelets play a crucial role in this process. It is usually used to quickly close blood vessel injuries to prevent bleeding. Another task of platelets is to respond to intruders. These include, for example Pathogens such as viruses and bacteriabut also Active substances from drugs.

Platelets respond to the components of the vaccine

According to the researchers, the platelets respond to the components of the vaccine. Certain platelet protein with label Platelet Factor 4 (PF4) is activated by the vaccine.

That immune system in return, it responds to it They make antibodies against PF4 and themselves in a row attacking each other. One can platelet aggregation thrombosis occurs and occurs.

Decrease in platelet count after adenovirus-based drugs

According to the research group after vaccination with adenovirus-based substances delayed decrease in platelet count (thrombocytopenia). “Poor alignment of your own immune system against your own body’s platelets”confirms Nicolai.

The exact mechanisms leading to VITT are currently being studied in detail by a working group led by Dr. Nicolai lit up. “By further exploring the exact response mechanisms, we want to help make vaccination with adenovirus-based techniques generally even safer in the future.”Nicolai explains.

It is not only relevant for vaccines

The focus is not only on COVID-19 vaccines from AstraZeneca or Johnson & Johnson. A similar reaction occurred, for example, after administration anticoagulant heparin known.

Injection affects the risk of thrombosis

In addition, the team was able to demonstrate in preliminary in vivo tests for the study that the risk of exaggerated immune system reactions after vaccination with adenovirus-based vaccines increases if Accidental intervention in a blood vessel during injection. This is not the case with proper muscle application.

“We believe that this project will help to better understand the interaction between platelets and the immune system in other cardiovascular diseases, thus contributing prospectively to basic research and heart health.”, sums up Professor Voigtländer. (vb)

Author and resource information

This text complies with the requirements of the medical literature, medical guidelines and current studies and has been reviewed by healthcare professionals.


Postgraduate editor (FH) Volker Blašek


  • Deutsche Herzstiftung eV / German Heart Research Foundation: From “helper” to “enemy”: Platelets can cause thrombosis due to incorrect immune response (published: June 23, 2022),
  • Leo Nicolai, Alexander Leunig, Kami Pekayvaz, et al .: Thrombocytopenia and splenic platelets controlled immune response after intravenous administration of ChAdOx1 nCov-19; in: Blood (2022),

Important note:
This article contains general advice only and should not be used for self-diagnosis or treatment. It can’t replace a doctor’s visit.

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