Dizziness/When she gets up, she feels dizzy/dizziness (main concern); syncope; nausea; Myalgia; chills; Weakness; syncope; fever; Felt really bad; Pain; she felt really weak/was weak (another main concern)/When she gets up, she feels weak; The day after I felt like I had the flu.; Chills/woke up with chills; her arm was sore/muscle aches/her arm was in bits/body aches; Had little nausea; arm was sore; Dizziness; SQ route of administration; This spontaneous case was reported by a consumer and describes the occurrence of the first episode of SYNCOPE (syncope) and the second episode of SYNCOPE (syncope) in a 63-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch nos. 041L21A, 0316Z0A and 001B21A) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.     Concurrent medical conditions included Allergic reaction to analgesics (Codeine), Asthma, Hypertension, Psoriatic arthritis and Immune disorder (NOS) (immune compromised). Concomitant products included MONTELUKAST SODIUM (SINGULAIR) for Asthma, METOPROLOL SUCCINATE (TOPROL XL) and ACETYLSALICYLIC ACID (BABY ASPIRIN) for Hypertension, PRAVASTATIN for an unknown indication.   On 14-Feb-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Subcutaneous) 1 dosage form. On 15-Mar-2021, received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Subcutaneous) dosage was changed to 1 dosage form. On 18-Aug-2021, received third dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Subcutaneous) dosage was changed to 1 dosage form. On 18-Aug-2021, the patient experienced INCORRECT ROUTE OF PRODUCT ADMINISTRATION (SQ route of administration). On 19-Aug-2021, the patient experienced VACCINATION COMPLICATION (Felt really bad). 19-Aug-2021, the patient experienced PAIN (Pain), ASTHENIA (she felt really weak/was weak (another main concern)/When she gets up, she feels weak), INFLUENZA LIKE ILLNESS (The day after I felt like I had the flu.), CHILLS (Chills/woke up with chills), MYALGIA (her arm was sore/muscle aches/her arm was in bits/body aches) and NAUSEA (Had little nausea). 19-Aug-2021, the patient experienced VACCINATION SITE PAIN (arm was sore), DIZZINESS (Dizziness) and PYREXIA (fever). On 20-Aug-2021, the patient experienced the first episode of SYNCOPE (syncope) (seriousness criterion medically significant). On 24-Aug-2021, the patient experienced the second episode of SYNCOPE (syncope) (seriousness criterion medically significant), NAUSEA (nausea), MYALGIA (Myalgia), CHILLS (chills) and ASTHENIA (Weakness). 24-Aug-2021, the patient experienced DIZZINESS (Dizziness/When she gets up, she feels dizzy/dizziness (main concern)). On 20-Aug-2021, ASTHENIA (she felt really weak/was weak (another main concern)/When she gets up, she feels weak), MYALGIA (her arm was sore/muscle aches/her arm was in bits/body aches), NAUSEA (Had little nausea), DIZZINESS (Dizziness) and PYREXIA (fever) had resolved. On 28-Aug-2021, last episode of SYNCOPE (syncope), INFLUENZA LIKE ILLNESS (The day after I felt like I had the flu.), CHILLS (Chills/woke up with chills), NAUSEA (nausea), MYALGIA (Myalgia), CHILLS (chills) and ASTHENIA (Weakness) had resolved. At the time of the report, VACCINATION COMPLICATION (Felt really bad), DIZZINESS (Dizziness/When she gets up, she feels dizzy/dizziness (main concern)), PAIN (Pain) and VACCINATION SITE PAIN (arm was sore) outcome was unknown and INCORRECT ROUTE OF PRODUCT ADMINISTRATION (SQ route of administration) had resolved.            Treatment information was not provided.   It was reported that patient had received the Moderna vaccine one and two without any side effects. Due to being immune compromised, patient received the third Moderna booster. The day after at 6:00 am patient felt like she had the flu, had temperature, body aches, chills, syncope, and weak. The next day she was ok. On day 6,  on 24 AUG 2021 at 06:00 am patient experienced the same symptoms but only worse. That lasted about 4 more days, was getting a little better each day.  Based on the current available information and temporal association between the use of the product and the start date of the events, a causal relationship cannot be excluded.  Clarification has been requested regarding the report of a medication error related to incorrect administration route of the vaccine.   Most recent FOLLOW-UP information incorporated above includes: On 04-Sep-2021: Significant ADR form received. Patient medical history, demographics, allergies, vaccination details, concomitant medication details and event onset time added, outcome of Fever, chills, asthenia, myalgia  updated from unknown to recovered and  new events added as Influenza like illness, condition aggravated and syncope and  Case upgrading to serious upon the receipt of follow up.; Sender's Comments: Based on the current available information and temporal association between the use of the product and the start date of the events, a causal relationship cannot be excluded.  Clarification has been requested regarding the report of a medication error related to incorrect administration route of the vaccine.