• Investigating the mechanisms of thrombosis caused by the injection of Covid 19 mRNA vaccines
  • Tahereh Rezazadeh,1,* Mona Adel,2 Sara Nemati,3 Alireza Jalalvand,4
    1. Department of Biology, East Tehran Branch, Islamic Azad University, Tehran, Iran
    2. Department of Biology, East Tehran Branch, Islamic Azad University, Tehran, Iran
    3. Department of Biology, East Tehran Branch, Islamic Azad University, Tehran, Iran
    4. Department of Influenza and Other Respiratory Viruses, Pasteur Institute of Iran, Tehran, Iran


  • Introduction: COVID19 infection has become the world's major concern from 2019, and no fully effective medicine has been introduced to treat this disease. Therefore, vaccination is the best strategy to deal with this disease, and so far, a large number of vaccines have been designed and produced on different platforms. Of these, mRNA vaccines have made a significant contribution to vaccination because they have advantages such as high safety, efficacy, and easier production. Unfortunately, one of the commonly reported side effects of this type of vaccine is thrombosis in some people. This study aims to investigate the possible mechanisms of thrombosis.
  • Methods: By searching the term" intitle: "mRNA vaccine" AND thrombosis AND coronavirus OR SARS-CoV-2" in the Google Scholar search engine. Numerous articles were reviewed and screened, and 11 articles were finally carefully investigated.
  • Results: Many studies have reported different mechanisms for clot formation due to the injection of vaccines containing mRNA. The vaccine based on ribonucleic acid contains mRNA that produces Protein S. Protein C and S work together to inactivate two important coagulation factors, V and VII. Also, A-II (Angiotensin II), which normally should be deactivated by binding to ACE-2, in another mechanism, due to the binding of Protein S1 subunit to ACE-2 and its inactivation, remains active and by releasing aldosterone and raising blood pressure participates in the formation of clots. Another mechanism is the contamination of platelets with mRNA. In this case, Protein S that is inside the platelet starts multiplying intensely. Faced with this amount of Protein S, the body orders the production of anti-platelet antibodies, which leads to the death of platelets and ultimately the formation of clots. On the other hand, if the person's body has a high level of antibodies or is infected with SARS-CoV-2 during that vaccination period, after the injection, if a strong immune response is created and the complement system is activated, resulting in the death of the vaccinated cell, a large quantity of Protein S and its fragments are released into the blood, in addition to increasing the probability of clot formation, it also leads to abnormal glycosylation of IgG. Another path of clot formation is the presence of antibodies that are produced against spike glycoproteins and cross-react with myocardial contractile proteins. Due to the increased incidence of clots in men, research has shown that testosterone can inhibit anti-inflammatory immune cells and induce a powerful immune response of the T helper lymphocyte type. In contrast, estrogen has inhibitory effects on pro-inflammatory T cells, thereby reducing the cellular immune response. Also, the immune system may recognize the mRNA contained in the vaccine as an antigen, which leads to the activation of inflammatory cascades and immune pathways.
  • Conclusion: Since mRNA-based vaccines are considered a new platform, knowing and understanding the mechanisms of clot formation in mRNA-based vaccines allows scientists to continue their research to eliminate the side effects of these vaccines. The current study has investigated the mechanisms involved in causing thrombosis by injecting this vaccine platform.
  • Keywords: mRNA vaccine, Covid 19, thrombosis, and protein S