COVID-Arm; Left arm is swollen from shoulder to elbow; flushing; Feel cold; Jittery/Feeling jittery; Fatigue; chills; left arm began to feel warm; Not feeling well; dozing; mild itching; left sore arm where I had received the vaccination/ warmth developed into a burning sensation; red rash had developed on the side of the arm near the vaccination site; about the size of the palm; Headache; sore arm; This spontaneous case was reported by a consumer (subsequently medically confirmed) and describes the occurrence of PAIN IN EXTREMITY (sore arm), FEELING JITTERY (Jittery/Feeling jittery), VACCINATION SITE SWELLING (Left arm is swollen from shoulder to elbow), FLUSHING (flushing) and VACCINATION SITE WARMTH (left arm began to feel warm) in a 65-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch no. 010A21A) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.     The patient's past medical history included Mast cell activation syndrome on 20-Dec-2015, Dysautonomia (general) on 09-Sep-2018 and Venous insufficiency on 01-Oct-2020. Previously administered products included for an unreported indication: cortisone. Past adverse reactions to the above products included Adverse reaction to product with cortisone. Concurrent medical conditions included Egg allergy, Iodine allergy, Latex allergy and Food allergy (Wheat). Concomitant products included ELECTROLYTES NOS from 15-Jan-2021 to an unknown date for Dysautonomia and Low BP, ASCORBIC ACID (VITAMIN C ASC ACID) from 15-Dec-2015 to an unknown date for Mast cell activation syndrome, POTASSIUM CHLORIDE from 15-Feb-2020 to an unknown date for Venous insufficiency and Restless legs.    On 26-Feb-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) 1 dosage form. On 26-Feb-2021, the patient experienced PAIN IN EXTREMITY (sore arm) and HEADACHE (Headache). On 09-Mar-2021, the patient experienced FEELING JITTERY (Jittery/Feeling jittery), VACCINATION SITE WARMTH (left arm began to feel warm), MALAISE (Not feeling well), SOMNOLENCE (dozing), VACCINATION SITE PRURITUS (mild itching), VACCINATION SITE PAIN (left sore arm where I had received the vaccination/ warmth developed into a burning sensation), VACCINATION SITE RASH (red rash had developed on the side of the arm near the vaccination site; about the size of the palm), FATIGUE (Fatigue) and CHILLS (chills). On 10-Mar-2021, the patient experienced VACCINATION SITE SWELLING (Left arm is swollen from shoulder to elbow), FLUSHING (flushing) and FEELING COLD (Feel cold). On an unknown date, the patient experienced VACCINATION SITE REACTION (COVID-Arm). On 01-Mar-2021, PAIN IN EXTREMITY (sore arm) and HEADACHE (Headache) had resolved. On 12-Mar-2021, FEELING JITTERY (Jittery/Feeling jittery), FLUSHING (flushing) and CHILLS (chills) had resolved. On 16-Mar-2021, VACCINATION SITE RASH (red rash had developed on the side of the arm near the vaccination site; about the size of the palm) had resolved. On 20-Mar-2021, VACCINATION SITE SWELLING (Left arm is swollen from shoulder to elbow) had resolved. On 27-Mar-2021, VACCINATION SITE REACTION (COVID-Arm) had resolved. On 28-Mar-2021, VACCINATION SITE WARMTH (left arm began to feel warm), MALAISE (Not feeling well), FEELING COLD (Feel cold), SOMNOLENCE (dozing), VACCINATION SITE PRURITUS (mild itching), VACCINATION SITE PAIN (left sore arm where I had received the vaccination/ warmth developed into a burning sensation) and FATIGUE (Fatigue) had resolved.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On 09-Mar-2021, Vital signs measurement: normal (normal) normal.     The action taken with mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) was unknown.       Additional medical history of the patient included serious adverse reactions to anti-histamines.  Treatment medicines were not included  Action taken with mRNA-1273 in response to the event was unknown   This case was linked to US-MODERNATX, INC.-MOD-2021-079069.   Most recent FOLLOW-UP information incorporated above includes: On 30-Mar-2021: Follow up information was received on 30-Mar-2021. Patient demographics added. outcome of the events, concomitant medications, medical history and medication history was added.; Reporter's Comments: Based on the current available information and temporal association between the use of the product and the start date of the event, a causal relationship cannot be excluded.