Frequency of antiplatelet antibodies in patients with thrombocytopenia after SARS-CoV-2 vaccination

Background

Thrombocytopenia has been reported as a complication following vaccination against SARS-CoV-2. We analyzed clinical data and antiplatelet antibodies of patients who developed de-novo or recurrent thrombocytopenia in temporal relationship to SARS-CoV-2 vaccination.

Methods

Sera of patients with thrombocytopenia (platelet count < 150 Gpt/L) sent to the Greifswald laboratory after SARS-CoV-2 vaccination between March 1st 2021 and March 31st 2022 were tested for antiplatelet antibodies against glycoprotein (GP) IIb/IIIa, GPIb/IX/V and GPIa/IIa by the indirect monoclonal antibody-specific immobilization of platelet antigens (MAIPA) assay. Anti-platelet factor 4 (PF4) antibodies were tested by IgG specific ELISA. Clinical features (age, sex, vaccine type and date of vaccination, bleeding symptoms) of patients were extracted from the laboratory submission form.

Results

We identified 156 patients (68 females, median age: 57 years) with thrombocytopenia who tested negative for anti-PF4 antibodies: after vector-based (n=74), mRNA-based (n=72), or a heterologous, first vector-based + second mRNA-based vaccination (n=10). Median platelet count was 33 Gpt/L and symptom onset was 5 days post-vaccination. Antiplatelet antibodies were found after different vaccination schemes to a similar extend: vector-based vaccines 25.7%; mRNA-based vaccines 22.2%; and heterologous vaccinations 30%. Patients testing positive for antiplatelet antibodies had lower platelet counts (Fig.1) and reported more often bleeding symptoms.

Conclusion

In general, vaccination against SARS-CoV-2 is a safe measure to control the COVID-19 pandemic, but patients who experience new bleeding symptoms a few days after vaccination with low platelet counts might be screened for antiplatelet antibodies. In this study, we found antiplatelet antibodies in about 20-30% of patients, which suggests a similar pathogenesis but independent of the type of vaccine.

Offenlegung Interessenkonflikt:

Andreas Greinacher reports grants and non-financial support from Aspen, Boehringer Ingelheim, MSD, Bristol Myers Squibb (BMS), Paringenix, Bayer Healthcare, Gore Inc., Rovi, Sagent, Biomarin/Prosensa, personal fees from Aspen, Boehringer Ingelheim, MSD, Macopharma, BMS, Chromatec, Werfen (Instrumentation Laboratory), and nonfinancial support from Boehringer Ingelheim, Portola, Ergomed, GTH e.V., Universitätsmedizin Greifswald is one of the owners of a patent for a solid phase assay to detect HIT and VITT antibodies.