Passing out; Pain in left breast; dizzy; Felt achy all over after she received the booster/Ache all over; a terrible headache after she received the booster/Headache; swelling under left arm lymph nodes/swelling under arm after she received the booster/Lump node under arm; left arm hurt after she received the booster; Fainting after she received the booster/Fainting; sick to stomach after she received the booster/Sick to stomach; felt weak and not herself after she received the booster/Feeling very weak; felt weak and not herself after she received the booster/had to lay back in bed; blurred vision; Heart racing fast/pulse went up to 104 bpm after receiving booster; This spontaneous case was reported by a consumer and describes the occurrence of LOSS OF CONSCIOUSNESS (Passing out) and SYNCOPE (Fainting after she received the booster/Fainting) in a 76-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch nos. 939905 and 004C2114) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.     Concurrent medical conditions included Atrial fibrillation, Blood pressure high, Drug allergy, Food allergy and Allergy NOS. Concomitant products included METOPROLOL, LEVOTHYROXINE SODIUM (SYNTHROID) and VALSARTAN (DIOVAN) for an unknown indication.   On 19-Apr-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) 1 dosage form. On 17-May-2021, received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) dosage was changed to 1 dosage form. On 05-Dec-2021, received third dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) dosage was changed to 1 dosage form. On 06-Dec-2021, the patient experienced SYNCOPE (Fainting after she received the booster/Fainting) (seriousness criterion medically significant), ABDOMINAL DISCOMFORT (sick to stomach after she received the booster/Sick to stomach), VISION BLURRED (blurred vision), PALPITATIONS (Heart racing fast/pulse went up to 104 bpm after receiving booster), DIZZINESS (dizzy), MYALGIA (Felt achy all over after she received the booster/Ache all over) and VACCINATION SITE PAIN (left arm hurt after she received the booster). 06-Dec-2021, the patient experienced ASTHENIA (felt weak and not herself after she received the booster/Feeling very weak), FEELING ABNORMAL (felt weak and not herself after she received the booster/had to lay back in bed), HEADACHE (a terrible headache after she received the booster/Headache) and LYMPHADENOPATHY (swelling under left arm lymph nodes/swelling under arm after she received the booster/Lump node under arm). On an unknown date, the patient experienced LOSS OF CONSCIOUSNESS (Passing out) (seriousness criterion medically significant) and BREAST PAIN (Pain in left breast). At the time of the report, LOSS OF CONSCIOUSNESS (Passing out), SYNCOPE (Fainting after she received the booster/Fainting), ABDOMINAL DISCOMFORT (sick to stomach after she received the booster/Sick to stomach), ASTHENIA (felt weak and not herself after she received the booster/Feeling very weak), FEELING ABNORMAL (felt weak and not herself after she received the booster/had to lay back in bed), VISION BLURRED (blurred vision), PALPITATIONS (Heart racing fast/pulse went up to 104 bpm after receiving booster), BREAST PAIN (Pain in left breast), DIZZINESS (dizzy), MYALGIA (Felt achy all over after she received the booster/Ache all over) and VACCINATION SITE PAIN (left arm hurt after she received the booster) outcome was unknown and HEADACHE (a terrible headache after she received the booster/Headache) and LYMPHADENOPATHY (swelling under left arm lymph nodes/swelling under arm after she received the booster/Lump node under arm) had not resolved.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On 06-Dec-2021, Heart rate: 104 (High) pulse went up to 104 bpm after receiving booster.         No history of myocarditis or pericarditis. No treatment information was provided.  Company Comment - This case concerns a 76-year-old, female patient with relevant medical history of atrial fibrillation, who experienced the serious expected event of syncope and the unexpected event of loss of consciousness. The event syncope occurred approximately 1 day after the third dose of mRNA-1273 vaccine. The event loss of consciousness occurred on an unknown date. The rechallenge was not applicable as event occurred after booster dose. However, this patient underlying medical condition remains a contributory factor. The benefit-risk relationship of mRNA-1273 (Moderna covid-19 vaccine) is not affected by this report.   This case was linked to MOD-2021-406388 (Patient Link).   Most recent FOLLOW-UP information incorporated above includes: On 07-Dec-2021: Upon Internal Review on 24-JAN-2022 non significant corrections were performed to change the listedness of the event Syncope On 26-Jan-2022: Follow up information included : New event passing out and breast pain were added, start date added for dose 2 and 3, Allergy to medications, food and other products were added; Sender's Comments: This case concerns a 76-year-old, female patient with relevant medical history of atrial fibrillation, who experienced the serious expected event of syncope and the unexpected event of loss of consciousness. The event syncope occurred approximately 1 day after the third dose of mRNA-1273 vaccine. The event loss of consciousness occurred on an unknown date. The rechallenge was not applicable as event occurred after booster dose. However, this patient underlying medical condition remains a contributory factor. The benefit-risk relationship of mRNA-1273 (Moderna covid-19 vaccine) is not affected by this report.