hyper eosinophilic syndrome (HES); eosinophilic asthma; Irregularity in heart and lung; Caller has been very very sick; She had COVID Disease twice in late 2020 and in Mid-May-2022; This spontaneous case was reported by a patient and describes the occurrence of HYPEREOSINOPHILIC SYNDROME (hyper eosinophilic syndrome (HES)) in a 57-year-old female patient who received mRNA-1273 (Spikevax) (batch no. 002M21A) for COVID-19 prophylaxis. The occurrence of additional non-serious events is detailed below.     The patient's past medical history included COVID-19 (She had COVID Disease in late 2020) in 2020. Previously administered products included for Drug use for unknown indication: Ibuprofen (Takes Ibuprofen from time to time but does not remember if she took it during COVID-19 vaccination). Past adverse reactions to the above products included No adverse event with Ibuprofen. Concurrent medical conditions included Meniere's disease (Taking Medication Triamterene 37.5ml) since 2019. Concomitant products included TRIAMTERENE for Meniere's disease.    On 18-Apr-2022, the patient received fourth dose of mRNA-1273 (Spikevax) (unknown route) 1 dosage form. In May 2022, the patient experienced COVID-19 (She had COVID Disease twice in late 2020 and in Mid-May-2022). On an unknown date, the patient experienced HYPEREOSINOPHILIC SYNDROME (hyper eosinophilic syndrome (HES)) (seriousness criterion medically significant), ASTHMA (eosinophilic asthma), HEART RATE IRREGULAR (Irregularity in heart and lung) and ILLNESS (Caller has been very very sick). The patient was treated with MEPOLIZUMAB (NUCALA) ongoing since an unknown date for Hypereosinophilic syndrome, at a dose of UNK UNK, qmo. At the time of the report, HYPEREOSINOPHILIC SYNDROME (hyper eosinophilic syndrome (HES)), ASTHMA (eosinophilic asthma), HEART RATE IRREGULAR (Irregularity in heart and lung) and ILLNESS (Caller has been very very sick) had not resolved and COVID-19 (She had COVID Disease twice in late 2020 and in Mid-May-2022) outcome was unknown.        For mRNA-1273 (Spikevax) (Unknown), the reporter did not provide any causality assessments.   She had no other vaccines at the same time or within 4 weeks of her COVID-19 vaccines.  On 23-Mar-2021, the patient received first monovalent dose (Lot: 002B21A).  On 20-Apr-2021, the patient received second monovalent dose (Lot: 043B21A).  On 18-Nov-2021, the patient received first Monovalent Booster dose (Lot: 004F21A).  Patient was normally a very healthy person.   In the past year and half she started developing symptoms and was diagnosed with hyper eosinophilic syndrome (HES). She had eosinophilic asthma. A bone marrow biopsy was not done yet. She had heart and lung stuff going on. Could have possibly affected their skin. Irregularity in heart and lung and fatigue was outrageous. She never wanted to believe it would be the Moderna vaccination. She was very very sick. At the time of report, she was on Nucala to bring the eosinophils down. They did steroid and they were a good temperature fix.  The patient was not a sue person but has had to see 5 doctors. Finally, patient's immunologist said this was not good and long term.  She states that she does not want Moderna safety to follow up with her doctor for now. She provided consent for Moderna Safety to follow up with her.  Company comment: This is a spontaneous case concerning a 57-year-old female patient with no relevant medical history reported, who experienced the unexpected serious (medically significant) event of hypereosinophilic syndrome among other non-serious events. The event occurred after the fourth dose of mRNA-1273 vaccine.  It was reported that the symptoms started in the past one year and a half. Patient was reviewed by several doctors. Treatment with Nucala and steroids. No further information disclosed about diagnostic tests performed or treatments received. At the time of the report, event was not resolved. The benefit-risk relationship of mRNA-1273 vaccine is not affected by this report. Events seriousness assessed as reported.   Most recent FOLLOW-UP information incorporated above includes: On 13-Sep-2023: Live follow-up information received included added medical history, concomitant medication, treatment medication details added, added event and updated narrative.