Page 187 - Haematologica May 2022

Letters to the Editor
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Figure 1. Clinical course of three separate cases of immune thrombocytopenia following COVID-19 vac- cination. (A) An 82-year-old male with newly diag- nosed immune thomrbocytopenia (ITP) was treated with dexamethasone an initially responded, received influenza vaccination, relapsed, and responded again to another pulse of dexamethasone and wean- ing prednisone taper. (B) An 83-year-old female with newly diagnosed ITP was treated with two pulses of dexamethasone/IVIg. (C) A 73-year-old female had a relapse of chronic ITP after receiving ChAd vaccina- tion, received IVIg 2 g/kg over 2 days as monothera- py. ChAd: ChAdOx1 nCoV-19 (AstraZeneca); IVIg: intravenous immunoglobulin.
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after the first, relapsing again on day 15 with a platelet count of 14x109/L before returning to her stable baseline within a further 7 days.
Our case series of vaccine-associated ITP comprises more cases of ITP following administration of the ChAd vaccine than after the BNT vaccine (12 from 3.2 million ChAd vaccinations vs. 2 from 1 million BNT), although there may be an ascertainment bias due to greater scruti- ny of patients following ChAd vaccination, as suggested in a recent Scottish study even though this paper also concluded that there was an increased rate of ITP diag- noses of 1.13 per 100,000 doses.9 In contrast, a Scandinavian epidemiological study was unable to iden- tify an increased rate of ITP diagnoses although rates of “unspecified thrombocytopenia” and bleeding events were increased significantly.13 Our study was not designed to address the questions of frequency or causal- ity. Our designation of these cases as “vaccine-associat- ed” ITP as opposed to co-incident ITP is based on the clinical diagnosis of ITP as one of exclusion. As vaccine association cannot be excluded, we cannot conclude that these patients have primary ITP, conceding that future outcomes may eventually justify revision of our diagno-
sis, which is common in ITP.14
Two of 14 cases are confounded at presentation by the
recent administration of influenza vaccination, and another patient received influenza vaccination shortly after initial recovery from ITP before relapsing. However, these limitations reflect an unavoidable real-world dilem- ma as public health imperatives to protect populations at risk during a pandemic will likely outweigh the consider- ably smaller numerical risk of uncertain outcomes and vaccination side effects when immunization programs overlap.
Most cases responded rapidly to first-line therapy although the majority remained on corticosteroids for at least 30 days (median prednisone equivalent dose 13.75 mg daily for all cases, 20 mg daily for those with newly diagnosed ITP). Patients whose chronic ITP relapsed after vaccination responded rapidly to first-line therapies, con- sistent with other observations,8 and reassuringly for those with underlying ITP who are at present hesitant to receive COVID-19 vaccination. So far, in three patients, a single pulse of high-dose dexamethasone was insufficient to maintain remission in this cohort, but repeat courses have been successful and well tolerated. Additional
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