Thrombosis with thrombocytopenia syndrome uncommon however critical hostile occasion related to Ad26.COV2.S vaccination

A current research performed in the US has revealed that thrombosis with thrombocytopenia syndrome following adenoviral vector-based coronavirus illness 2019 (COVID-19) vaccination is a uncommon occasion. Nevertheless, the situation may cause critical penalties as soon as developed, together with hospitalization, intensive care unit (ICU) admission, and even dying. The research is at the moment accessible on the medRxiv* preprint server whereas awaiting peer assessment.

Study: Case Series of Thrombosis with Thrombocytopenia Syndrome following COVID-19 vaccination--United States, December 2020-August 2021. Image Credit: Kateryna Kon / Shutterstock


Amongst at the moment accessible COVID-19 vaccines, two are primarily based on adenoviral vectors (ChAdOx1 nCoV-19 by Oxford/AstraZeneca and Ad26.COV2.S by Janssen/Johnson & Johnson). Just a few circumstances of thrombosis and thrombocytopenia have been noticed amongst vaccine recipients after these vaccines have been rolled out. Due to this adversity, some European nations and the US have paused the administration of those vaccines and thought of mRNA-based COVID-19 vaccines for mass immunization.  

Within the US, the prevalence of thrombosis with thrombocytopenia syndrome has been 13 – 39 circumstances per million vaccine doses administered. The syndrome shares some traits of autoimmune heparin-induced thrombocytopenia. In keeping with accessible literature, the manufacturing of anti-platelet issue 4 (PF4) antibodies by adenoviral DNA or adenoviral vector-induced splice variants of SARS-CoV-2 spike protein is the primary causative issue for thrombosis with thrombocytopenia syndrome. These antibodies set off the event of thrombosis by activating platelets.

Within the present research, the scientists have totally investigated the prevalence of thrombosis with thrombocytopenia syndrome after COVID-19 vaccination within the US. Furthermore, they’ve evaluated the scientific penalties related to the syndrome.

Research design

The scientists collected case experiences of thrombosis and thrombocytopenia after COVID-19 vaccination from The Vaccine Opposed Occasions Reporting System, a surveillance system for reporting vaccine-related adversities within the US. They primarily centered on circumstances reported between December 14, 2020, and August 31, 2021.

Vital observations

Sufferers with thrombosis in an uncommon location (cerebral vein, visceral artery or vein, extremity artery, central artery or vein), or in an extremity vein or pulmonary artery, together with new-onset thrombopenia after vaccination have been thought of to have thrombosis with thrombocytopenia syndrome.

Based mostly on this definition, a complete of 52 circumstances have been recognized to have thrombosis with thrombocytopenia syndrome. Of those circumstances, 50 developed the syndrome after adenoviral vector-based vaccination (Ad26.COV2.S; Janssen/Johnson & Johnson), and a couple of developed after mRNA-based vaccination (Moderna COVID-19 vaccine).    

Contemplating the administration of 14 million doses of adenoviral vector-based vaccine and 351 million doses of mRNA-based vaccine, the prevalence of thrombosis with thrombocytopenia syndrome was estimated to be 3.55 per million Ad26.COV2.S doses and 0.0057 per million mRNA vaccine doses.

Thrombosis with thrombocytopenia syndrome after adenoviral vector-based vaccination  

The most typical location of thrombosis was cerebral venous sinuses, which was noticed in 54% of circumstances. In about 98% of circumstances, venous thrombosis or thromboembolism was recognized. Arterial thrombosis was recognized in 16% of circumstances.   

Generally, thrombosis was handled with heparin. Different therapies used to handle thrombosis with thrombocytopenia syndrome have been non-heparin anticoagulants, intravenous immunoglobulin, corticosteroids, platelet transfusion, and plasmapheresis. In 40% of circumstances, surgical procedure or radiologic remedy was carried out.  

All 50 sufferers with Ad26.COV2.S-induced thrombosis with thrombocytopenia syndrome have been admitted to the hospital. Of them, 64% have been admitted to the ICU, and 12% died finally.

Medical presentation of thrombosis with thrombopenia syndrome

Probably the most generally recognized preliminary symptom was a headache, and the typical period of symptom onset was 10 days after vaccination. The vast majority of sufferers with complications had cerebral venous sinus thrombosis.  

The sufferers who stayed within the hospital for greater than 20 days and people admitted to the ICU had considerably decrease platelet counts in comparison with different hospitalized sufferers. Thrombocytopenia was noticed in all hospitalized sufferers. In 84% of sufferers, anti-PF4 antibodies have been detected.

Thrombosis with thrombocytopenia syndrome after mRNA-based vaccination  

Solely two circumstances with thrombosis with thrombocytopenia syndrome have been recognized after mRNA vaccination. Each sufferers had cerebral venous sinus thrombosis, with one having deep vein thrombosis and pulmonary emboli.

The signs appeared 2 and 11 days after vaccination. Anti-PF4 antibodies have been current in each sufferers. Dying occurred in a single affected person throughout hospitalization.

Research significance

The research reveals that thrombosis with thrombocytopenia syndrome is comparatively uncommon after adenoviral vector-based COVID-19 vaccination. Nevertheless, individuals who develop the syndrome can expertise extreme penalties, together with hospitalization, ICU admission, and even dying.

As talked about by the scientists, extra research are required for the risk-benefit evaluation of COVID-19 vaccination.

*Vital Discover

medRxiv publishes preliminary scientific experiences that aren’t peer-reviewed and, subsequently, shouldn’t be thought to be conclusive, information scientific apply/health-related habits, or handled as established info.

#Thrombosis #thrombocytopenia #syndrome #uncommon #hostile #occasion #Ad26COV2S #vaccination

Leave a Comment