Cytokine release syndrome; This spontaneous case was reported by a consumer and describes the occurrence of CYTOKINE RELEASE SYNDROME (Cytokine release syndrome) in a 69-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 prophylaxis.     The patient's past medical history included Ovarian tumor benign in 2003, Heart attack in 2017, Breast tumor benign, Meniscus tear and Diverticulitis in September 2020. Concurrent medical conditions included Arthritis, Drug allergy (Allergic to Sulfa), Drug allergy (Allergic to Zocor), Drug allergy (Allergic to Pravachol), Drug allergy (Allergic to Spironolactone), Drug allergy (Allergic to Erythromycin), Ulcer, Fatigue, Hypertension (High blood pressure) and Hyperlipidemia (High cholestrol). Concomitant products included PREDNISONE, RAMIPRIL, CARVEDILOL, PANTOPRAZOLE, CHLORTHALIDONE, ROSUVASTATIN and TOCILIZUMAB (ACTEMRA) for an unknown indication.    In April 2021, the patient received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. In April 2021,  after starting mRNA-1273 (Moderna COVID-19 Vaccine), the patient experienced CYTOKINE RELEASE SYNDROME (Cytokine release syndrome) (seriousness criteria medically significant and life threatening). At the time of the report, CYTOKINE RELEASE SYNDROME (Cytokine release syndrome) had resolved.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On an unknown date, Platelet count: Off the charts as a result of CRS.         Treatment information was not reported. The patient reported that, 24 hours after receiving the Moderna vaccine, she developed CRS and her immune system started attacking itself.  Company comment: This spontaneous case concerns a 69 year old female with underlying medical history of ovarian tumor, breast tumor and diverticulitis along with concomitant use of tocilizumab who experienced the unexpected serious (life threatening, medically significant) adverse event of special interest cytokine release syndrome which occurred approximately 24 hours after receiving the second dose of mRNA1273. The patient reported that post vaccination her immune system started attacking itself and as a result of the CRS her platelet count was "off the charts".  Further details regarding the clinical course, hospital admission, other diagnostic or imaging test done and treatment were not provided. The patient's underlying multiple comorbidities that affect the immune system, namely her ovarian and breast tumor, diverticulitis and concomitant use of tocilizumab may be considered as risk factors for developing cytokine release syndrome.  Information regarding other COVID-19 vaccines were not reported. The benefit-risk relationship of mRNA-1273 vaccine is not affected by this report.   Reporter did not allow further contact; Sender's Comments: This spontaneous case concerns a 69 year old female with underlying medical history of ovarian tumor, breast tumor and diverticulitis along with concomitant use of tocilizumab who experienced the unexpected serious (life threatening, medically significant) adverse event of special interest cytokine release syndrome which occurred approximately 24 hours after receiving the second dose of mRNA1273. The patient reported that post vaccination her immune system started attacking itself and as a result of the CRS her platelet count was "off the charts".  Further details regarding the clinical course, hospital admission, other diagnostic or imaging test done and treatment were not provided. The patient's underlying multiple comorbidities that affect the immune system, namely her ovarian and breast tumor, diverticulitis and concomitant use of tocilizumab may be considered as risk factors for developing cytokine release syndrome.  Information regarding other COVID-19 vaccines were not reported. The benefit-risk relationship of mRNA-1273 vaccine is not affected by this report.