ISTH Congress Abstracts

Official abstracts site for the ISTH Congress

MENU 

ITP before and after COVID-19 vaccinations: a national cohort study

1The Canberra Hospital, Garran, Australian Capital Territory, Australia, 2Liverpool Hospital, Sydney, New South Wales, Australia, 3Department of Haematology, Westmead Hospital, Sydney, New South Wales, Australia, 4Royal Adelaide Hospital, Adelaide, South Australia, Australia, 5Calvary Matery Hospital, Newcastle, New South Wales, Australia, 6Department of Clinical Hematology, The Alfred Hospital, Melbourne, Australia AND Department of Medicine, Central Clinical School, Monash University, Melbourne, Australia, Melbourne, Victoria, Australia, 7ANZAC Research Institute, University of Sydney; Department of Haematology, Concord Repatriation General Hospital, Sydney, New South Wales, Australia, 8Royal Perth Hospital, Perth, Western Australia, Australia, 9St George Hospital, Sydney, New South Wales, Australia, 10Mid North Coast Haematology, Port Macquarie, New South Wales, Australia, 11Fiona Stanley Hospital, Perth, Western Australia, Australia, 12Princess Alexandra Hospital, Woolloongabba, Queensland, Australia

Abstract Number: PB1198

Meeting: ISTH 2022 Congress

Theme: Platelet Disorders, von Willebrand Disease and Thrombotic Microangiopathies » Acquired Thrombocytopenias

Background: Immune thrombocytopenia (ITP) has been reported following COVID-19 vaccination. From a population of over 20 million eligible vaccine recipients in Australia, over 32 million doses have been administered: 19,600,000 Pfizer BNT162b2 (BNT), 12,600,000 AstraZeneca ChAdOx1 nCoV-19 (ChAd), and 397,000 Moderna mRNA-1273.

Aims: Describe a comprehensive series of ITP after vaccination with clinical outcomes.

Methods: After obtaining IRB approval (2021/ETH00723), we collected data on all ITP cases diagnosed by haematologists in Australia within six weeks of any COVID-19 vaccination. We analysed their outcomes using international consensus definitions of responses and WHO bleeding.

Results: Demographics (n=50), treatments, and platelet outcomes (Figures A and B). Bleeding was mostly minor: 35/50 (70%) WHO score < 2. Compared to relapses of prior ITP, new presentations of ITP were significantly associated with ChAd over BNT (OR 7.1: 95% CI 1.7 to 25.7, P=0.0124*). Most patients responded quickly and deeply: median TTR 4 days (IQR 2-7), median TTCR 7 days (IQR 4-19), overall RR 45/47 (96%), and CR 40/45 (89%). Gender, age, antecedent influenza vaccination and severity of thrombocytopenia had no significant impact on: bleeding at presentation, response rates, relapse rates, time to response, or the need for ongoing treatments at day 90. No patients presented with thrombosis. PF4 ELISA was positive in one of 18 cases after ChAd (functional testing was negative).

Conclusion(s): We diagnosed ITP more frequently after ChAd than BNT vaccination, occurring de novo after 1st doses. Ascertainment bias cannot be excluded due to greater scrutiny for platelet related complications, but almost all patients in this cohort needed treatment.

Standard first-line treatments for ITP are highly effective for both de novo and prior ITP (96%), but second-line therapies are often required (34%).

Our data reaffirms the safety of vaccinating patients with pre-existing ITP, as bleeding is mild (92% WHO < 2) and platelets respond quickly (TTCR 5 days).

Table

Patient demographics and treatments used.

Image

Platelet counts before and after vaccination.

To cite this abstract in AMA style:

Choi P, Hsu D, Curnow J, TAN C, Enjeti A, Tran H, CHEN V, Yong A, Roncolato F, Simpson J, Pepperell D, Bird R. ITP before and after COVID-19 vaccinations: a national cohort study [abstract]. https://abstracts.isth.org/abstract/itp-before-and-after-covid-19-vaccinations-a-national-cohort-study/. Accessed September 21, 2023.

« Back to ISTH 2022 Congress

ISTH Congress Abstracts - https://abstracts.isth.org/abstract/itp-before-and-after-covid-19-vaccinations-a-national-cohort-study/