key: cord-0774200-xx7jclo3 authors: Al-Ahmad, Mona; Al Rasheed, Mona; Shalaby, Neveen; Rodriguez-Bouza, Tito; Altourah, Lulwa title: Immune Thrombocytopenia (ITP): Relapse Versus de novo After COVID-19 Vaccination date: 2022-02-02 journal: Clin Appl Thromb Hemost DOI: 10.1177/10760296211073920 sha: 40f76637bcb7f390e80e3a5442d242c65255cb86 doc_id: 774200 cord_uid: xx7jclo3 nan Our institution does not require ethical approval for reporting individual cases or case series. Verbal informed consent was obtained from the patient(s) for their anonymized information to be published in this article. Supplemental materials: All data can be accessed directly from the corresponding author upon a formal request. With the development of the new COVID-19 vaccines, recent case reports and series were published linking COVID-19 vaccines to immune thrombocytopenia (ITP) onset or relapse. [1] [2] [3] We describe case series of ten patients with thrombocytopenia during the first 4 weeks after COVID-19 vaccination. Data was collected from first January to 31 st July 2021. None of the patients described had SARS-CoV-2 infection at the time of ITP diagnosis or relapse. None of the patients reported with thrombocytopenia prior to COVID-19 vaccination. A case-by-case description has been included in the supplement and a summary of results are found in Table 1 . From January first -July 31 st 2021 in Kuwait, 1,029,417 individuals had received the first dose only and 716,296 had received both doses of Pfizer vaccine, and 736,123 patients had received the first dose only and 289,592 had received both doses of AstraZeneca/Oxford vaccine. We describe 10 cases of ITP; three cases were de novo and 7 cases were ITP relapse after the vaccine which represent 1:927,000 cases of all vaccinated individuals in Kuwait (January first-July 31 st , 2021). Two out of 10 cases developed ITP after the first dose of AstraZeneca/ Oxford which represented 1:368,000 of all individuals who received first dose of the AstraZeneca/Oxford. One developed de novo ITP after the second dose of Pfizer vaccine which represents 1:1,750,000 of all patients who received both doses of Pfizer vaccine. All cases of ITP de novo were females, age range of 33 to 56 years, with time range between vaccine exposure and platelet count drop of 7 to 21 days and a platelet count range of 2 to 10 × 10 9 /l. All patients required hospitalization and active treatment and two required second line therapy with thrombopoietin receptor agonists. Two patients had only partial response after 3 days and one had complete remission 10 days after the second admission. Our cases varied in the timing of ITP onset ranging 4 to 21 days post vaccine, similar to a study by Lee et al. which showed that ITP relapse ranges 1 to 23 days post vaccine. 2 However, this is in contrast to reported cases by Helms et al. that occurred one day post Moderna vaccine 3 and by Tarawneh et al. that occurred three days post Pfizer vaccine. 1 The cases presented here included different age groups (19-63 years) than those reported by others. [1] [2] [3] The incidence of de novo ITP in Kuwait is very low (almost 1:1,000,000) of all vaccinated individuals in with difference in the incidence according to the type of vaccine (1: 368,000 for AstraZeneca/Oxford and 1:1.750,000 for Pfizer vaccine). Unfortunately, data on ITP prevalence in the population is × This paper is intended to raise awareness of the possibility of the occurrence of ITP relapse post COVID-19 vaccine like other vaccines previously reported. We presented ten cases, three of whom developed de novo ITP. We do not advice against COVID-19 vaccination of such individuals but rather suggest performing CBC few days prior to and after vaccination aiming for an earlier discovery of ITP attack to provide a proper intervention as soon as possible, hence preventing undiagnosed severe thrombocytopenia, bleeding, and the need for aggressive therapy or hospital admission. Author's contribution MA and MA initiated and coordinated the development of the paper, worked on data collection, analysis, and writing up the paper. MA, MA, NS, TR and LA analyzed and interpreted the results and helped in writing introduction. All authors read and approved the final manuscript. The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. The author(s) received no financial support for the research, authorship and/or publication of this article. Neveen Shalaby https://orcid.org/0000-0002-4251-5251 Tito Rodriguez-Bouza https://orcid.org/0000-0001-7474-9397 Supplemental material for this article is available online. Immune thrombocytopenia in a 22-year-old post covid-19 vaccine Thrombocytopenia following Pfizer and Moderna SARS-CoV-2 vaccination Severe, refractory immune thrombocytopenia occurring after SARS-CoV-2 vaccine