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Journal of Current Science and Technology

ISSN 2630-0656 (Online)

Unusual blood clots with low blood platelets from Covid-19 viral vector vaccines

  • Pantapat Chokpitakkul, Shrewsbury International School Bangkok, Talat Noi, Samphanthawong, Bangkok , Thailand,


In providing human immunity from the SARS-CoV-2 virus, AstraZeneca’s ChAdOx1 nCov-19 vaccines have been administered in multiple nations around the world.  Throughout this literature review, the background behind derivation of this vaccine from chimpanzees to avoid pre-existing human immunity to this adenoviral vector’s mechanism of interactions will be discussed prior to clinical issues this vaccine brings.  Arranged in sections, this discussion concerns the adenovector vaccine’s ability to induce both innate and adaptive immunity, featuring the mucosal route of administration’s ability to stimulate tissue-resident memory T cells (TRM), a crucial part of the adaptive immune system.  Despite its solid ability to stimulate immunity with high efficiency and efficacy, a surge in female fatalities following administrations of the ChAdOx1 nCov-19 adenovector vaccines have also occurred.  Published articles regarding both hypothesised mechanisms as well as recorded incidences of this rare vaccine-induced blood clots, also known as the Thrombosis and Thrombocytopenia Syndrome (TTS), have been discussed.  Despite still lacking a causal relationship between AZ administrations in heparin-free patients and TTS incidences, all of these articles have implied the mechanisms inducing this condition arise from an induction of platelet-activating antibodies against PF4.  The most plausible arisal of these antibodies is from free DNA molecules within the ChAdOx nCov-19 vaccine.  Additionally, TTS draws similarities to autoimmune heparin-induced thrombocytopenia cases, where a platelet count decline also occurs.

Keywords: adenoviral vectors; ChAdOx nCov-19; PF4; vaccine-induced immune thrombotic thrombocytopenia

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DOI: 10.14456/jcst.2022.14


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