unstable enough to need help walking anywhere; needs help walking; forced her to change her lifestyle significantly; Blacked out; vomiting; Incapacitating muscle ache in left shoulder; strong arm pain in left shoulder; vertigo; dizziness; pain in the left side of her neck/couldn't move her neck; got a 3rd dose of the Moderna Covid-19 Vaccine in her left arm despite not being immunocompromised; This spontaneous case was reported by a consumer and describes the occurrence of LOSS OF CONSCIOUSNESS (Blacked out) in an 84-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch nos. 053E21A, 032L20A and 011L20A) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.     Concurrent medical conditions included Osteoporosis. Concomitant products included METOPROLOL, CALCIUM, VITAMIN D3 and MAGNESIUM for an unknown indication.   On 04-Jan-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On 04-Feb-2021, received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) dosage was changed to 1 dosage form. On 26-Aug-2021, received third dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) dosage was changed to 100 microgram. On 26-Aug-2021, the patient experienced OFF LABEL USE (got a 3rd dose of the Moderna Covid-19 Vaccine in her left arm despite not being immunocompromised). On 12-Sep-2021, the patient experienced PAIN IN EXTREMITY (strong arm pain in left shoulder), VERTIGO (vertigo), DIZZINESS (dizziness), NECK PAIN (pain in the left side of her neck/couldn't move her neck) and VOMITING (vomiting). 12-Sep-2021, the patient experienced ARTHRALGIA (Incapacitating muscle ache in left shoulder). On an unknown date, the patient experienced LOSS OF CONSCIOUSNESS (Blacked out) (seriousness criterion medically significant), BALANCE DISORDER (unstable enough to need help walking anywhere) and GAIT DISTURBANCE (needs help walking). The patient was treated with PREDNISONE for Adverse event, at an unspecified dose and frequency. At the time of the report, LOSS OF CONSCIOUSNESS (Blacked out), BALANCE DISORDER (unstable enough to need help walking anywhere), GAIT DISTURBANCE (needs help walking) and VOMITING (vomiting) outcome was unknown, OFF LABEL USE (got a 3rd dose of the Moderna Covid-19 Vaccine in her left arm despite not being immunocompromised), PAIN IN EXTREMITY (strong arm pain in left shoulder), NECK PAIN (pain in the left side of her neck/couldn't move her neck) and ARTHRALGIA (Incapacitating muscle ache in left shoulder) had resolved and VERTIGO (vertigo) and DIZZINESS (dizziness) had not resolved.        For mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown), the reporter did not provide any causality assessments.   She performed an Epley Maneuver for dizziness, but it caused her to temporarily black out. It also made the dizziness worse. dizziness. Patient reported that Every night when she got up during the night and every morning when arising, she was dizzy and unstable enough to need help walking anywhere. The dizziness tends to subside somewhat by early afternoon. After that, she generally felt closer to normal and steadier on legs, able to take a 30 minute walk.  On 23SEP2021, she even ran a bit, optimistic that problems were over. On the contrary, the next morning, 24SEP2021, the dizziness was even worse than before.   This case was linked to MOD-2021-331002 (Patient Link).   Most recent FOLLOW-UP information incorporated above includes: On 29-Sep-2021: Follow up received contains Reporter details, Patient details, Medical history, Product details, Concomitant drugs, New events.; Sender's Comments: This is a case of an Off-label use of the vaccine that concerns an 84-year-old female patient with no relevant medical history who received a third dose of the mRNA-1273 (Moderna COVID-19 Vaccine), who experienced the unexpected event of Loss of Consciousness. The event occurred on an unknown date after the third dose of mRNA-1273 (Moderna COVID-19 Vaccine). The rechallenge was not applicable since only information about the third dose was disclosed. The benefit-risk relationship of mRNA-1273 (Moderna COVID-19 Vaccine)  is not affected by this report.