Physicians' Academy for Cardiovascular Education

Clinical resemblance of heparin-induced thrombocytopenia in some cases after COVID-19 vaccination

A Prothrombotic Thrombocytopenic Disorder Resembling Heparin-Induced Thrombocytopenia Following Coronavirus-19 Vaccination

Literature - Greinacher A, Thiele T, Warkentin TE et al. - Research Square 2021 (NOT PEER-REVIEWED),

Introduction and methods

In the battle against the COVID-19 pandemic, vaccines against SARS-CoV-2 have been developed as countermeasure. The European Medical Agency (EMA) approved 4 vaccines between December 2020 and March 2021: a nucleoside modified mRNA COVID-19 vaccine (Pfizer/BioNTech); an mRNA-based vaccine encapsulated in lipid nanoparticle (Moderna); a recombinant adenoviral (ChAdOx1) vector encoding the spike protein antigen of SARS-CoV-2, AZD1222 (AstraZeneca); and a recombinant adenovirus type 26 vector encoding SARS-CoV-2 spike glycoprotein COVID-19 Vaccine (Janssen).

In the EU, ~55 million doses of vaccines have been administered by March 2021. Some cases of thrombotic events combined with thrombocytopenia have been reported in patients after COVID-19 vaccination.

This study describes 9 patients presenting with prothrombotic thrombocytopenia beginning 4 to 16 days after COVID-19 vaccination with AZD1222 in Austria and Germany from February-March 2021. Because of resemblance to heparin-induced thrombocytopenia (a prothrombotic thrombocytopenic disorder triggered by heparin and other anions), sera was collected from 4 patients and analyzed for platelet-activating antibodies directed against platelet factor 4 (PF4)/heparin by enzyme-immunoassay (EIA).

Main results


Moderate to severe thrombocytopenia combined with thrombotic complications at unusual sites starting ~one week after COVID-19 vaccination by AZD1222 observed in some cases suggest a disorder clinically resembling heparin-induced thrombocytopenia, but with a different serological profile.

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