key: cord-0883259-y7kib49q authors: Paulsen, Finn-Ole; Schaefers, Christoph; Langer, Florian; Frenzel, Christian; Wenzel, Ulrich; Hengel, Felicitas E.; Bokemeyer, Carsten; Seidel, Christoph title: Immune Thrombocytopenic Purpura after Vaccination with COVID-19 Vaccine (ChAdOx1 nCov-19) date: 2021-07-27 journal: Blood DOI: 10.1182/blood.2021012790 sha: e3c2490b1f6e13cbc555840476ebac90d3da5b35 doc_id: 883259 cord_uid: y7kib49q nan One vaccine available is the adenovirus-vector based ChAdOx1 nCov-19, also known as 43 AZD122 from AstraZeneca 3,4 . As this vaccine is considered to be safe 2-4 , a new condition 44 named vaccine-induced immune thrombotic thrombocytopenia (VITT) syndrome was 45 reported in relation to prior administration of ChAdOx1 nCov-19 [5] [6] [7] and Ad26.COV2.S 46 (Janssen Pharmaceuticals), respectively 8 . 47 As VITT is associated with thrombocytopenia accompanied by thrombosis and antibodies 49 against platelet factor 4 (PF4) in the serum, it differs from post-vaccination Immune 50 Thrombocytopenic Purpura (ITP), a phenomenon associated to both live and inactivated 51 vaccines 9-11 . The latter, however, to our knowledge has not yet been described in 52 association with the administration of ChAdOx1 nCov-19. 53 Here, we report the findings in a cohort of four patients who presented with severe 55 thrombocytopenia in absence of thrombosis after application of ChAdOx1 nCoV-19 56 adenoviral vector vaccine presenting within a short period of time at a single center 57 institution. 58 59 We conducted a retrospective and prospective analysis of patients that received treatment 61 in our institution for ITP in association with ChAdOx1 nCoV19 vaccination within a 19-day 62 period in May 2021. Patient's records were evaluated, and the diagnosis of ITP was 63 confirmed. Demographic and clinical characteristics are presented in Table 1 . As no patient presented with signs or symptoms of thrombotic events and no antibodies to 89 PF4-polyanion complexes were found in ELISA (Asserachrom® HPIA-IgG, Stago), the cases 90 presented are not associated with VITT. Additionally, an MRI scan was conducted in patient 91 2 to rule out intracranial bleeding and cerebral vein or sinus thrombosis due to her 92 presentation with headaches. A bone marrow biopsy of patient 2 revealed an increased 93 megakaryocyte count without signs of malignancy. No clinical signs or symptoms of 94 infection were present in any patient. Based on the presentation and after ruling out 95 differential diagnoses, ITP was diagnosed in all four patients 12 . 96 97 Treatment and patient outcomes patients 3 and 4 due to quick recovery and increasing platelet counts to 23 x 10 9 /L and 101 98 x 10 9 /L after four and six days, respectively. Patients 3 and 4 were discharged for 102 outpatient follow-up with a steroid reduction plan. 103 104 Additionally, intravenous immunoglobulin (IVIG) was administered in patients 1 (0.4 g/kg) 105 and 2 (1g/kg, Fig 1) . As patient 2 did not respond, dexamethasone (40mg) was initiated for 106 seven more days. As platelet counts increased in patients 1 (142 × 10 9 /L) and 2 (46 × 10 9 /L) 107 as shown in Fig. 1 , the patients were discharged. Seven days later, at the first outpatient 108 visit, patient 2 presented with platelet counts < 5 × 10 9 /L and readmission was conducted 109 for treatment with corticosteroids (prednisolone 100mg) and IVIGs (1g/kg). We present four patients with symptomatic thrombocytopenia in association with prior 120 administration of ChAdOx1 nCov-19. 121 Of note, three of four patients presented with a past medical history known to be 122 associated with the occurrence of ITP or thrombocytopenia, such as thyroid disorders or 123 preexisting mild thrombocytopenia. However, platelet counts in all patients were stable 124 before administration of ChAdOx1 nCov-19. As no patient presented with signs of 125 thrombotic events and antibodies to PF4-polyanion, thrombocytopenia was not associated 126 with VITT. adults/year 17 , we must debate that our findings might be coincidental. However, post-145 vaccination thrombocytopenia after immunization to several diseases such as rubella 11 , 146 pneumococcus 10 , and influenza 9 is an already known phenomenon and is presumed to be 147 linked to hyperfunction of B-cells as seen in ITP 18, 19 . Moreover, considering previous years, 148 we counted an average of only one patient per month being admitted to our department 149 for ITP, meaning a fourfold increase within a time period of only 19 days. Epidemiology Based on Current Evidence Safety of COVID-19 187 vaccines administered in the EU: Should we be concerned? 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