Extreme fatigue; Nocturnal fever of 105 degree F/high fever; Blood cancer returned; Thrombocytopenia; Bleeding from mouth; Weak; Anemia; Body stiffness; Shaking; Bed wetting; Sleeping; teeth chattering chills/teeth chattering; sweat soaked bed; cannot sleep nights; constant urination; this night I'm going to die; balance problems/ Balance disorder; Panicked; This spontaneous case was reported by a consumer (subsequently medically confirmed) and describes the occurrence of FATIGUE (Extreme fatigue), PYREXIA (Nocturnal fever of 105 degree F/high fever), ACUTE MYELOID LEUKAEMIA RECURRENT (Blood cancer returned) and THROMBOCYTOPENIA (Thrombocytopenia) in a 76-year-old male patient who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.     The patient's past medical history included Neutropenia, Escherichia coli bacteremia and Bone marrow biopsy (Negative) in February 2021. Concurrent medical conditions included Atrial fibrillation (alternating with a very slow heart beat), Kidney stone, Diverticulitis, BPH, Pancytopenia and Acute myeloid leukemia. Concomitant products included VENETOCLAX (VENCLEXTA) and DECITABINE (DACOGEN) for Acute myeloid leukemia, POTASSIUM, AMOXICILLIN, CLAVULANIC ACID (AUGMENTIN [AMOXICILLIN;CLAVULANIC ACID]), VITAMINS NOS, PROBIOTICS NOS and FOLIC ACID, IRON (IRON & FOLIC ACID) for an unknown indication.    On 07-Apr-2021, the patient received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) 1 dosage form. On 09-Apr-2021, the patient experienced FATIGUE (Extreme fatigue) (seriousness criterion hospitalization) and PYREXIA (Nocturnal fever of 105 degree F/high fever) (seriousness criterion hospitalization). In April 2021, the patient experienced HYPERHIDROSIS (sweat soaked bed), INSOMNIA (cannot sleep nights), POLLAKIURIA (constant urination), FEAR OF DEATH (this night I'm going to die), BALANCE DISORDER (balance problems/ Balance disorder), PANIC REACTION (Panicked) and CHILLS (teeth chattering chills/teeth chattering). On an unknown date, the patient experienced ACUTE MYELOID LEUKAEMIA RECURRENT (Blood cancer returned) (seriousness criterion medically significant), THROMBOCYTOPENIA (Thrombocytopenia) (seriousness criterion medically significant), MOUTH HAEMORRHAGE (Bleeding from mouth), ASTHENIA (Weak), ANAEMIA (Anemia), MUSCULOSKELETAL STIFFNESS (Body stiffness), TREMOR (Shaking), ENURESIS (Bed wetting) and SOMNOLENCE (Sleeping). At the time of the report, FATIGUE (Extreme fatigue), PYREXIA (Nocturnal fever of 105 degree F/high fever), ACUTE MYELOID LEUKAEMIA RECURRENT (Blood cancer returned), THROMBOCYTOPENIA (Thrombocytopenia), HYPERHIDROSIS (sweat soaked bed), INSOMNIA (cannot sleep nights), POLLAKIURIA (constant urination), FEAR OF DEATH (this night I'm going to die), BALANCE DISORDER (balance problems/ Balance disorder), PANIC REACTION (Panicked), MOUTH HAEMORRHAGE (Bleeding from mouth), ASTHENIA (Weak), ANAEMIA (Anemia), MUSCULOSKELETAL STIFFNESS (Body stiffness), TREMOR (Shaking), ENURESIS (Bed wetting), SOMNOLENCE (Sleeping) and CHILLS (teeth chattering chills/teeth chattering) outcome was unknown.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On 09-Apr-2021, Body temperature: 105 degree f (High) High - degree F. On 09-Apr-2021, C-reactive protein: 4+ (abnormal) 4+. On 09-Apr-2021, Cardiac disorder: negative (Negative) Negative. On 09-Apr-2021, Chest X-ray: clear (normal) clear. On 09-Apr-2021, Full blood count: pancytopenia (abnormal) abnormal. On 09-Apr-2021, SARS-CoV-2 test: negative (Negative) Negative.         Treatment: The patient was taking ibuprofen (Motrin) and diphenhydramine (Benadryl). On 09-APR-2021 the laboratory data were done that includes  Blood culture and the results were unknown. On -Apr-2021, patient started therapy with Moderna COVID Vaccine for Covid 19  Company comment - This case concerns a 76-year-old male patient with relevant medical history of acute myeloid leukemia, pancytopenia and concurrent use of venetoclax and decitabine, who experienced serious unexpected events of fatigue, pyrexia, acute myeloid leukemia recurrent and thrombocytopenia. The events pyrexia and fatigue occurred approximately 2 days after the second dose of Spikevax. whereas the remaining events occurred unspecified time after the second dose. Rechallenge was not applicable since the events occurred after the second dose. Patient's concomitant use of venetoclax and decitabine is possible confounder for the event of thrombocytopenia whereas patient's history of acute myeloid leukemia is possible confounder for the event of acute myeloid leukemia reccure.  The benefit-risk relationship of drug is not affected by this report   Most recent FOLLOW-UP information incorporated above includes: On 01-Oct-2021: Follow up received on 1-OCT-2021 that contains Events added and concurrent conditions was updated. Narrative updated.; Sender's Comments: This case concerns a 76-year-old male patient with relevant medical history of acute myeloid leukemia, pancytopenia and concurrent use of venetoclax and decitabine, who experienced serious unexpected events of fatigue, pyrexia, acute myeloid leukemia recurrent and thrombocytopenia. The events pyrexia and fatigue occurred approximately 2 days after the second dose of Spikevax. whereas the remaining events occurred unspecified time after the second dose. Rechallenge was not applicable since the events occurred after the second dose. Patient's concomitant use of venetoclax and decitabine is possible confounder for the event of thrombocytopenia whereas patient's history of acute myeloid leukemia is possible confounder for the event of acute myeloid leukemia reccure.  The benefit-risk relationship of drug is not affected by this report