key: cord-1015883-je1i8fql
authors: De Stefano, Valerio; Candelli, Marcello; Rossi, Elena; Franceschi, Francesco
title: Response to correspondence in reference to the previously published Epub manuscript: immune thrombocytopenic purpura after SARS‐CoV‐2 vaccine
date: 2021-06-25
journal: Br J Haematol
DOI: 10.1111/bjh.17631
sha: 36f9c39760c4789b3bd65a83aaf4982d1cd9de36
doc_id: 1015883
cord_uid: je1i8fql

nan

1 De novo ITP after vaccination is a well-known condition. 2 A co-incidental occurrence of ITP arising after vaccination is possible but unlikely. On Sunday, 14 February 2021, 29 744 individuals had been vaccinated against SARS-CoV-2 in Italy (7 058 with Vaxzevriaâ; https://lab24.ilsole24ore.com/numeri-vaccini-italia-mondo/ #vaccinazioni-giorno-per-giorno, accessed 16 May 2021).

Considering an annual incidence of 2Á9/100 000 personyears 3 , the expected number of cases during three weeks should be one over 602 409, with a likelihood of occurrence of 1Á17% in a cohort of 7 058 subjects. Moreover, the patient's platelet count in a blood examination of 2019 was 208 9 10 9 /l. Therefore, we consider a causal relationship with vaccination more likely rather than a co-incidence. . In our patient, the assay for anti-PF4 antibodies was carried out by chemiluminescence, which results negative in many cases positive by ELISA test 4 . However, no thrombosis at atypical sites was detected.

Therefore, we conclude that our patient suffered from vaccine-related isolated immune thrombocytopenia which was partially responsive to steroid treatment. Physicians should be aware that thrombocytopenia after anti-SARS-CoV-2 vaccine may present as an isolated ITP not accompanied by the severe VITT syndrome to avoid undue anxiety. The VITT syndrome is never asymptomatic, but besides petechiae, easy bruising or bleeding it is accompanied also by one or more of the following symptoms related to vessel occlusion: severe headache, visual changes, abdominal pain, nausea and vomiting, back pain, shortness of breath, leg pain or swelling. [5] [6] [7] The increased D-dimer levels may induce the suspicion of thrombosis, but it may be non-specific and due to an inflammatory response after vaccination. After COVID-19, increased D-dimer levels persist up to four months after the infection 8 so that a similar occurrence can be hypothesized after vaccination. However, in thrombocytopenic cases with D-dimer levels exceedingly high [(above 4 000 FEU fibrinogen equivalent units), i.e., 2 000 ng/ml], investigation for thrombosis is cautiously recommended. 9

The conduct of this research did not need external financial support. 

Immune thrombocytopenic purpura after SARS-CoV-2 vaccine

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Epidemiology of incident immune thrombocytopenia: a nationwide population-based study in France

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