Vaccine related immune thrombocytopenia; This literature-non-study case was reported in a literature article and describes the occurrence of IMMUNE THROMBOCYTOPENIA (Vaccine related immune thrombocytopenia) in an 81-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 prophylaxis.   LITERATURE REFERENCE:     Concurrent medical conditions included Rheumatoid arthritis, Hypertension and Hypothyroidism. Concomitant products included HYDROCHLOROTHIAZIDE for Hypertension, LEVOTHYROXINE for Hypothyroidism, HYDROXYCHLOROQUINE for Rheumatoid arthritis.   On an unknown date, the patient received third dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On an unknown date, after starting mRNA-1273 (Moderna COVID-19 Vaccine), the patient experienced IMMUNE THROMBOCYTOPENIA (Vaccine related immune thrombocytopenia) (seriousness criteria hospitalization and medically significant). The patient was treated with IMMUNOGLOBULINS NOS (IMMUNOGLOBULIN I.V) (intravenous) at a dose of 1 gram per kilogram; PLATELETS at a dose of two units and DEXAMETHASONE at a dose of 40 milligram. At the time of the report, IMMUNE THROMBOCYTOPENIA (Vaccine related immune thrombocytopenia) was resolving.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On an unknown date, Alanine aminotransferase (46-142 U/L): 62 U/L Day of admission and 14 U/L Day of admission. On an unknown date, Aspartate aminotransferase (9-36 U/L): 17 U/L Day of admission. On an unknown date, Blood albumin (3.5-5.2 g/dL): 3.6 g/dL Day of admission. On an unknown date, Blood bilirubin (0.2-1.1 mg/dl): 0.3 mg/dl Day of admission. On an unknown date, Blood chloride (97-107 millimole per litre): 102 millimole per litre Day of admission. On an unknown date, Blood creatinine (0.60-1.10 mg/dl): 0.97 mg/dl Day of admission. On an unknown date, Blood fibrinogen (200-460 mg/dl): 485 mg/dl Day of admission. On an unknown date, Blood lactate dehydrogenase (116-250 U/L): 261 U/L Elevated Day of admission. On an unknown date, Blood potassium (3.7-4.8 millimole per litre): 4.8 millimole per litre Day of admission. On an unknown date, Blood pressure measurement: 133/66 mmHg. On an unknown date, Blood smear test: did not reveal any schistocytes. On an unknown date, Blood sodium (136-145 millimole per litre): 136 millimole per litre Day of admission. On an unknown date, Blood urea (8-23 mg/dl): 17 mg/dl Day of admission. On an unknown date, Body temperature: 98.1 degree F Day of admission. On an unknown date, Computerised tomogram head: found to be negative for any acute intracranial abnormality.. On an unknown date, Haemoglobin (11-15.5 g/dL): 12 g/dL Day of admission. On an unknown date, Haptoglobin (40-220 mg/dl): 167 mg/dl. On an unknown date, Heart rate: 60 beats per minute. On an unknown date, International normalised ratio (0.9-1.1): 1.0 Day of admission. On an unknown date, Mean cell volume (79-98 fL): 88 fL Day of admission. On an unknown date, Oxygen saturation: 95 % on room air. On an unknown date, Physical examination: patient had crusted old blood surrounding the nares, widespread petechiae, multiple bruises along the upper extremities, and petechiae on the chest.. On an unknown date, Platelet count (155-370 thousand per microlitre): 5 thousand per microlitre Day of admission, 37 thousand per microlitre after second unit of platelets, 18 thousand per microlitre Day 2 decreased overnight, 38 thousand per microlitre Day 3 after third unit of platelets, 62 thousand per microlitre Day 4 increased prior to discharge, 116 thousand per microlitre One-week follow-up, 134 thousand per microlitre Three-month follow-up and 168 thousand per microlitre Six-month follow-up. On an unknown date, Prothrombin time (12.2-14.2 secs): 13.1 secs Day of admission. On an unknown date, Respiratory rate: 16 breaths per minute Day of admission. On an unknown date, SARS-CoV-2 test: Negative. On an unknown date, Ultrasound abdomen: did not reveal splenomegaly. On an unknown date, White blood cell count (3.7-10.3 thousand per microlitre): 3.81 thousand per microlitre Day of admission.   For mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown), the reporter considered IMMUNE THROMBOCYTOPENIA (Vaccine related immune thrombocytopenia) to be related.    Patient presented with worsening epistaxis for four days. She described it as a progressively worsening oozing of blood. One day prior to the presentation, she started noticing large bruising on her arms. Her symptoms were accompanied by fatigue, mild headache, and bilateral leg swelling. She reported compliance with all prescribed medications and only noted her recent changes after receiving the third booster dose of the Moderna mRNA-1273 vaccine. Initial two doses of vaccination were completed approximately 10 months before the inciting vaccine. Each of her previous vaccines had been tolerated well without any similar symptoms or thrombocytopenia. The patient's platelet count was 332 × 10^3/uL two months prior to hospital presentation. Hydroxychloroquine was stopped on admission. On follow up patient had poor control of rheumatoid arthritis with steroids alone, she was restarted on hydroxychloroquine and the event did not reoccur. On regular follow-ups with hematology and rheumatology and exhibited a gradual improvement in platelet count on three- and six-month follow-ups.  The authors stated that considering the proximity of the COVID-19 booster to episode of profound thrombocytopenia, booster vaccination was considered the likely inciting factor, however, a multifactorial etiology is likely: a pre-existing autoimmune condition, as evidence suggests, the patient may be at an increased risk of relapse as well as post-vaccine autoimmune conditions, including immune thrombocytopenia. The authors further stated that although hydroxychloroquine has been linked to thrombocytopenia, the patient's prolonged course without symptoms and ability to restart medication without any difficulty make it unlikely for hydroxychloroquine to have caused her thrombocytopenia and some evidence suggests that hydroxychloroquine may actually be a suitable maintenance treatment for this condition.  Company Comment: This literature-non-study case report concerns an 81-year-old female patient with relevant medical history of Rheumatoid arthritis and Hypothyroidism, who experienced serious (due to hospitalization and medical significance) unexpected event of Immune thrombocytopenia that is an adverse event of special interest. Reportedly, the event occurred six days after the patient had received the mRNA-1273 vaccine (as booster vaccination). She presented to the emergency department with worsening epistaxis for four days. One day prior to the presentation, she started noticing large bruising on her arms that was accompanied by fatigue, mild headache, and bilateral leg swelling. On physical examination, the patient had crusted old blood surrounding the nares, widespread petechiae, multiple bruises along the upper extremities, and petechiae on the chest. The patient confirmed that initial two doses of vaccination (the exact product name was not specified) had been tolerated well without any similar symptoms or thrombocytopenia and also denied any history of marked bleeding, recently receiving heparin or blood products, or recent viral or gastrointestinal illness. Laboratory investigations revealed marked thrombocytopenia, elevated lactate dehydrogenase and fibrinogen. CT scan of the head found to be negative for any acute intracranial abnormality and an ultrasound of the abdomen did not reveal splenomegaly. PCR testing returned negative for COVID-19. The patient was treated with intravenous immunoglobulin, platelets units, and intravenous dexamethasone. The patient's platelet count continued to rise after the third unit of platelets. After discharge from hospital, the patient had regular follow-ups with hematology and rheumatology and exhibited a gradual improvement in platelet count on three- and six-month follow-ups. Due to poor control of rheumatoid arthritis with steroids alone, hydroxychloroquine was restarted and she did not have another episode of profound thrombocytopenia. As per the authors, the patient's pre-existing autoimmune condition is considered as confounding factor as the patient might be at an increased risk for post-vaccine autoimmune conditions, including immune thrombocytopenia. Hydroxychloroquine has been linked to thrombocytopenia, however, the patient's prolonged course without symptoms and ability to restart medication without reoccurrence of thrombocytopenia, as per the authors, it was unlikely that hydroxychloroquine caused her thrombocytopenia in this case and in addition, some evidence suggests that hydroxychloroquine may actually be a suitable maintenance treatment for this condition. The benefit-risk relationship of mRNA-1273 vaccine is not affected by this report. Sender's Comments: This literature-non-study case report concerns an 81-year-old female patient with relevant medical history of Rheumatoid arthritis and Hypothyroidism, who experienced serious (due to hospitalization and medical significance) unexpected event of Immune thrombocytopenia that is an adverse event of special interest. Reportedly, the event occurred six days after the patient had received the mRNA-1273 vaccine (as booster vaccination). She presented to the emergency department with worsening epistaxis for four days. One day prior to the presentation, she started noticing large bruising on her arms that was accompanied by fatigue, mild headache, and bilateral leg swelling. On physical examination, the patient had crusted old blood surrounding the nares, widespread petechiae, multiple bruises along the upper extremities, and petechiae on the chest. The patient confirmed that initial two doses of vaccination (the exact product name was not specified) had been tolerated well without any similar symptoms or thrombocytopenia and also denied any history of marked bleeding, recently receiving heparin or blood products, or recent viral or gastrointestinal illness. Laboratory investigations revealed marked thrombocytopenia, elevated lactate dehydrogenase and fibrinogen. CT scan of the head found to be negative for any acute intracranial abnormality and an ultrasound of the abdomen did not reveal splenomegaly. PCR testing returned negative for COVID-19. The patient was treated with intravenous immunoglobulin, platelets units, and intravenous dexamethasone. The patient's platelet count continued to rise after the third unit of platelets. After discharge from hospital, the patient had regular follow-ups with hematology and rheumatology and exhibited a gradual improvement in platelet count on three- and six-month follow-ups. Due to poor control of rheumatoid arthritis with steroids alone, hydroxychloroquine was restarted and she did not have another episode of profound thrombocytopenia. As per the authors, the patient's pre-existing autoimmune condition is considered as confounding factor as the patient might be at an increased risk for post-vaccine autoimmune conditions, including immune thrombocytopenia. Hydroxychloroquine has been linked to thrombocytopenia, however, the patient's prolonged course without symptoms and ability to restart medication without reoccurrence of thrombocytopenia, as per the authors, it was unlikely that hydroxychloroquine caused her thrombocytopenia in this case and in addition, some evidence suggests that hydroxychloroquine may actually be a suitable maintenance treatment for this condition. The benefit-risk relationship of mRNA-1273 vaccine is not affected by this report.