Immune thrombocytopenia and COVID-19 vaccination: Outcomes and comparisons to prepandemic patients

Essentials

• Immune thrombocytopenia (ITP) has been reported after COVID-19 vaccinations.

• Fifty cases of ITP after vaccination were reviewed for distinguishing features and treatment outcomes.

• Most cases (36 of 50) in our study presented after first-dose ChAdOx1 (AstraZeneca) vaccination.

• ITP after vaccination presents with infrequent bleeding and responds well to conventional treatments.

Abstract

Background

Immune thrombocytopenia (ITP) has been reported following COVID-19 vaccination. After index case fatalities, there was concern among patients both with and without a prior history of ITP in Australia.

Objectives

To describe treatment outcomes of ITP after COVID-19 vaccination and compare relapsed vs historical pre-COVID-19 ITP cohorts.

Methods

We collected ITP cases in Australia within 6 weeks of receiving any COVID-19 vaccination as part of primary vaccination (up to October 17, 2021). Second, we reviewed platelet charts in a historical ITP cohort to determine whether platelet variability was distinct from relapsed ITP after vaccination.

Results

We report on 50 patients (37 de novo, 13 relapsed ITP) vaccinated from March 22, 2021, to October 17, 2021. Although there was 1 fatality, bleeding was otherwise mostly minor: (70% WHO bleeding grade <2). De novo ITP was more likely after AstraZeneca ChAdOx1 nCoV-19 (89%) than Pfizer BNT162b2 (11%). Most patients responded quickly (median, 4 days; complete response, 40 of 45 [89%]). In the historical cohort, only 6 of 47 patients exhibited platelet variability (>50% decrease and platelets <100 × 10⁹/L), but median platelet nadir was significantly higher than vaccination relapse (27 vs 6 × 10⁹/L, P =.005).

Conclusion

ITP was more frequently reported after AstraZeneca ChAdOx1 nCoV-19 than Pfizer BNT162b2 vaccination. Standard ITP treatments remain highly effective for de novo and relapsed ITP (96%). Although thrombocytopenia can be severe after vaccination, bleeding is usually mild. Despite some sampling bias, our data do not support a change in treatment strategies for patients with ITP after vaccination.