Caused a mast cell activation syndrome flare.; Feeling hot; Hives; Restless legs syndrome; Yeast infection; Injection site became very red, swollen, bumpy and extremely itchy; Headache; Cold chills; Muscle ache; Nausea; Fatigue; Fever; General malaise; Itchiness; typical reaction; Sore at injection site; Swelling at injection site; Redness at inj site; This spontaneous case was reported by a consumer and describes the occurrence of MAST CELL ACTIVATION SYNDROME (Caused a mast cell activation syndrome flare.) in a 43-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch no. 025L20A) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.     The patient's past medical history included Asthma since an unknown date. Previously administered products included for Product used for unknown indication: Pneumovax (Temporary loss of use of arm where injected). Past adverse reactions to the above products included Adverse event with Pneumovax. Concurrent medical conditions included Mast cell activation syndrome since 2018, Celiac disease since 1999, Immunocompromised, Anaphylaxis, Hypersensitivity reaction, Hives, Hay fever, Alcohol allergy (Hives, facial flushing, fingling tongue and lips.), Mycobacterium avium complex infection since 2020 and Dermatitis herpetiformis since 1999. Concomitant products included VILAZODONE HYDROCHLORIDE (VIIBRYD) from 13-Nov-2020 to an unknown date for Depression, AZITHROMYCIN from 12-Jul-2020 to 21-Apr-2021, ETAMBUTOL [ETHAMBUTOL] from 14-Dec-2020 to 23-Apr-2021, CIMETIDINE (TAGAMET [CIMETIDINE]) and CETIRIZINE HYDROCHLORIDE (ZYRTEC [CETIRIZINE HYDROCHLORIDE]) for Mycobacterium avium complex infection, CURCUMIN for an unknown indication.    On 08-Jan-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) 1 dosage form. On 08-Jan-2021, the patient experienced INJECTION SITE REACTION (typical reaction), INJECTION SITE PAIN (Sore at injection site), INJECTION SITE SWELLING (Swelling at injection site) and INJECTION SITE ERYTHEMA (Redness at inj site). On 10-Jan-2021, the patient experienced PRURITUS (Itchiness). On 14-Jan-2021, the patient experienced RESTLESS LEGS SYNDROME (Restless legs syndrome), FUNGAL INFECTION (Yeast infection), SKIN REACTION (Injection site became very red, swollen, bumpy and extremely itchy), MALAISE (General malaise), HEADACHE (Headache), CHILLS (Cold chills), MYALGIA (Muscle ache), NAUSEA (Nausea), FATIGUE (Fatigue) and PYREXIA (Fever). On an unknown date, the patient experienced MAST CELL ACTIVATION SYNDROME (Caused a mast cell activation syndrome flare.) (seriousness criterion medically significant), FEELING HOT (Feeling hot) and URTICARIA (Hives). The patient was treated with RIFABUTIN on 11-Jan-2021 at an unspecified dose and frequency; KETOTIFEN (oral) ongoing from 20-Jan-2021 at a dose of 2 times a day; DIPHENHYDRAMINE HYDROCHLORIDE (BENADRYL [DIPHENHYDRAMINE HYDROCHLORIDE]) (oral) on 16-Jan-2021 at an unspecified dose and frequency and RIFAMPIN on 11-Jan-2021 at an unspecified dose and frequency. On 12-Jan-2021, INJECTION SITE PAIN (Sore at injection site), INJECTION SITE SWELLING (Swelling at injection site) and INJECTION SITE ERYTHEMA (Redness at inj site) had resolved. At the time of the report, MAST CELL ACTIVATION SYNDROME (Caused a mast cell activation syndrome flare.), RESTLESS LEGS SYNDROME (Restless legs syndrome), FUNGAL INFECTION (Yeast infection), MALAISE (General malaise), FEELING HOT (Feeling hot), URTICARIA (Hives), HEADACHE (Headache), CHILLS (Cold chills), MYALGIA (Muscle ache), NAUSEA (Nausea), FATIGUE (Fatigue) and PYREXIA (Fever) outcome was unknown and SKIN REACTION (Injection site became very red, swollen, bumpy and extremely itchy), PRURITUS (Itchiness) and INJECTION SITE REACTION (typical reaction) had not resolved.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On 15-Jan-2021, Body temperature: 100.6. On 15-Jan-2021, Heart rate: 97. On 15-Jan-2021, Oxygen saturation: 96 %. On 15-Jan-2021, SARS-CoV-2 test: Negative. On 16-Jan-2021, Body temperature: 100.9. On 18-Jan-2021, Body temperature: 101.3. On an unknown date, Body temperature: 100.8.     The action taken with mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) was unknown.       Company comment: Very limited information regarding this event (mast cell activation syndrome) has been provided at this time. Details regarding  the event HCP notes, diagnostics and treatment are required for further assessment. However, based on the current available information and temporal association between the use of the product and the start date of other non-serious events, a causal relationship cannot be excluded.   Most recent FOLLOW-UP information incorporated above includes: On 09-Jun-2021: Updated past medical history, lab data, and concomitant and treatment medications.  Case upgraded to serious. On 09-Jun-2021: Upon internal review on 08-DEC-2022 non-significant correction was performed to update "case received from field" to blank; Sender's Comments: Very limited information regarding this event (mast cell activation syndrome) has been provided at this time. Details regarding  the event HCP notes, diagnostics and treatment are required for further assessment. However, based on the current available information and temporal association between the use of the product and the start date of other non-serious events, a causal relationship cannot be excluded.