Had trouble moving around; When patient was discharged her WBC was 2 and then 2 days later she started getting fever of 102 degrees F; Anemic; Extremely fatigued, which never went away; Diagnosed with HLH; This spontaneous case was reported by a non-health professional and describes the occurrence of HAEMOPHAGOCYTIC LYMPHOHISTIOCYTOSIS (Diagnosed with HLH), FATIGUE (Extremely fatigued, which never went away), MOBILITY DECREASED (Had trouble moving around), ANAEMIA (Anemic) and PYREXIA (When patient was discharged her WBC was 2 and then 2 days later she started getting fever of 102 degrees F) in a 58-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch nos. 016M20A and 048A21A) for COVID-19 vaccination.     The patient's past medical history included Bone marrow biopsy (bone marrow biopsy procedures) since an unknown date, Chemotherapy, Blood transfusion and Platelet transfusion.   On 12-Feb-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) 1 dosage form. On 12-Mar-2021, received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) dosage was changed to 1 dosage form. On 13-Mar-2021, the patient experienced FATIGUE (Extremely fatigued, which never went away) (seriousness criteria hospitalization and life threatening). On 17-Mar-2021, the patient experienced ANAEMIA (Anemic) (seriousness criteria hospitalization and life threatening). On an unknown date, the patient experienced HAEMOPHAGOCYTIC LYMPHOHISTIOCYTOSIS (Diagnosed with HLH) (seriousness criteria hospitalization, medically significant and life threatening), MOBILITY DECREASED (Had trouble moving around) (seriousness criteria hospitalization and life threatening) and PYREXIA (When patient was discharged her WBC was 2 and then 2 days later she started getting fever of 102 degrees F) (seriousness criteria hospitalization, medically significant and life threatening). The patient was hospitalized for 30 days due to HAEMOPHAGOCYTIC LYMPHOHISTIOCYTOSIS. At the time of the report, HAEMOPHAGOCYTIC LYMPHOHISTIOCYTOSIS (Diagnosed with HLH), FATIGUE (Extremely fatigued, which never went away), MOBILITY DECREASED (Had trouble moving around), ANAEMIA (Anemic) and PYREXIA (When patient was discharged her WBC was 2 and then 2 days later she started getting fever of 102 degrees F) outcome was unknown.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On 17-Mar-2021, Blood test: abnormal (abnormal) anemic. On 17-Mar-2021, Body temperature: 102 (abnormal) 102. On 17-Mar-2021, Haemoglobin: 8 (Low) Anemic. On 17-Mar-2021, Platelet disorder: 80 (abnormal) 80. On 17-Mar-2021, White blood cell count: 2 (abnormal) 2. On an unknown date, Blood test: abnormal (abnormal) she became more anemic. On an unknown date, Haemoglobin: low (Low) down. On an unknown date, Platelet disorder: 30 (abnormal) 30, 93 from 250 (abnormal) 93 from 250, low (Low) Low, low (Low) dropped more and low (Low) platelet kept on dropping. On an unknown date, White blood cell count: 1.5. (abnormal) 1.5. and came back up (normal) came back up.         Patient was hospitalized 3 times and had undergone chemotherapy.  She was given with WBC injection (multiple shots) and her WBC came back up. She was treated with steroids also. Few days later she needed blood transfusion again.  During hospitalization hematology department had done test like bone marrow biopsy multiple times, CT scans. And then was diagnosed with HLH, which was a super rare and aggressive immune response disease. She had blood tests daily and more transfusions. At certain point she needed platelet transfusion also.   Treatment included Chemotherapy and a drug named JAKAFI, which is not yet approved by FDA for HLH.   On 17 Jun 2021, She had chemo for 7 weeks and she responded well.  Company Comment :Very limited information regarding this event/s has been provided at this time. Further information has been requested. Further information is not expected.   Reporter did not allow further contact; Sender's Comments: Very limited information regarding this event/s has been provided at this time. Further information has been requested. Further information is not expected.