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Impact of SARS-CoV- 2 vaccination in thrombotic thrombocytopenic purpura patients
Research and Practice in Thrombosis and Haemostasis Conference ; 6(Supplement 1), 2022.
Article in English | EMBASE | ID: covidwho-2128124
ABSTRACT

Background:

Thrombotic thrombocytopenic purpura (TTP) has occasionally been described after vaccination. Since the availability of anti-SARS- CoV- 2 vaccines, 12 cases have been described on a possible association with TTP onset. Aim(s) This study aims to evaluate the relapse rates in patients affected by TTP undergoing anti-SARS- CoV- 2 vaccination. Method(s) All consecutive TTP patients undergoing anti-SARS- CoV- 2 vaccination from March to May 2021 were enrolled. Blood samples were collected before vaccination (T0), 2 weeks after the first (T1) and the second dose (T2) to evaluate ADAMTS13 activity and anti-ADAMTS13 antibody titer. Result(s) A total of 49 TTP patients were enrolled (48 acquired and 1 congenital), all vaccinated with an mRNA vaccine. No patients had a clinical TTP relapse, with an ADAMTS13 relapse rate of 1.36% per month. Mean levels of ADAMTS13 activity were stable among the three timepoints (Figure). In only two patients a significant drop in ADAMTS13 levels occurred after the first dose (from 28% to <3% and from 101% to 82%), and both remained stable after the second dose, with negative anti-ADAMTS13 antibodies. Due to a stable undetectable ADAMTS13, the first patient was treated with 4 doses of weekly 375 mg/m2 rituximab with a rapid ADAMTS13 response. One patient had positive basal anti-ADAMTS13 antibodies with a titer remaining stable after the two vaccine doses, while in another patient anti-ADAMTS13 antibodies became detectable after the first dose, with no corresponding drop in ADAMTS13 levels and a stable titer after the second dose. Conclusion(s) The result of our study prospectively evaluating the effect of anti-SARS- CoV- 2 vaccination on the risk of relapse in a large cohort of patients with TTP in Milan showed a lower than reported relapse rate (1.36% vs 2.6%) with an observed to expected incidence rate ratio of 0.52, confirming the safety of mRNA-based anti-SARS- CoV- 2 vaccination in TTP patients.
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Full text: Available Collection: Databases of international organizations Database: EMBASE Type of study: Experimental Studies Topics: Vaccines Language: English Journal: Research and Practice in Thrombosis and Haemostasis Conference Year: 2022 Document Type: Article

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Full text: Available Collection: Databases of international organizations Database: EMBASE Type of study: Experimental Studies Topics: Vaccines Language: English Journal: Research and Practice in Thrombosis and Haemostasis Conference Year: 2022 Document Type: Article