fluttering of heart; drowsy/still drowsy/drowsiness is really bad/it's been days now and I'm still suffering; dizzy; very bad side effects/I was doing well until I got this booster/this is a very bad side effect; couldn't even hardly move on Friday, Saturday, and Sunday; lower extremities, toes are hot at night and cold in the morning; woke up on Friday morning and I was falling down; couldn't walk; anxious; received 2 doses of Pfizer BioNTech vaccine; received 2 doses of Pfizer BioNTech vaccine; This spontaneous case was reported by a patient and describes the occurrence of CARDIAC FLUTTER (fluttering of heart) in a female patient of an unknown age who received mRNA-1273 BIVALENT .222 (MODERNA COVID-19 VACCINE, BIVALENT (ORIGINAL AND OMICRON BA.4/BA.5)) for COVID-19 prophylaxis. The occurrence of additional non-serious events is detailed below.     Previously administered products included for Product used for unknown indication: pfizer COVID-19 VACCIN PFIZER INJVLST 0 and3MLCOVID-19 VACCIN PFIZER INJVLST (Patient received two doses of the Pfizer COVID-19 vaccine as well as two booster doses of Pfizer). Past adverse reactions to the above products included No adverse event with pfizer COVID-19 VACCIN PFIZER INJVLST 0 and3MLCOVID-19 VACCIN PFIZER INJVLST. Concurrent medical conditions included Cane user (Patient was able to stand now with a cane.). Concomitant products included RIVAROXABAN (XARELTO) for an unknown indication.    On an unknown date, the patient received fifth dose of mRNA-1273 BIVALENT .222 (MODERNA COVID-19 VACCINE, BIVALENT (ORIGINAL AND OMICRON BA.4/BA.5)) (unknown route) 1 dosage form. On an unknown date, the patient experienced CARDIAC FLUTTER (fluttering of heart) (seriousness criterion medically significant), SOMNOLENCE (drowsy/still drowsy/drowsiness is really bad/it's been days now and I'm still suffering), DIZZINESS (dizzy), IMMUNISATION REACTION (very bad side effects/I was doing well until I got this booster/this is a very bad side effect), HYPOKINESIA (couldn't even hardly move on Friday, Saturday, and Sunday), FEELING OF BODY TEMPERATURE CHANGE (lower extremities, toes are hot at night and cold in the morning), FALL (woke up on Friday morning and I was falling down), GAIT INABILITY (couldn't walk), ANXIETY (anxious), INTERCHANGE OF VACCINE PRODUCTS (received 2 doses of Pfizer BioNTech vaccine) and COVID-19 IMMUNISATION (received 2 doses of Pfizer BioNTech vaccine). At the time of the report, CARDIAC FLUTTER (fluttering of heart), SOMNOLENCE (drowsy/still drowsy/drowsiness is really bad/it's been days now and I'm still suffering), DIZZINESS (dizzy), IMMUNISATION REACTION (very bad side effects/I was doing well until I got this booster/this is a very bad side effect), HYPOKINESIA (couldn't even hardly move on Friday, Saturday, and Sunday), FEELING OF BODY TEMPERATURE CHANGE (lower extremities, toes are hot at night and cold in the morning), GAIT INABILITY (couldn't walk) and ANXIETY (anxious) had not resolved, FALL (woke up on Friday morning and I was falling down) outcome was unknown and INTERCHANGE OF VACCINE PRODUCTS (received 2 doses of Pfizer BioNTech vaccine) and COVID-19 IMMUNISATION (received 2 doses of Pfizer BioNTech vaccine) had resolved.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On an unknown date, Heart rate: Increased.         Patient was good and normal prior to getting the vaccine. Patient  was currently on the way to her eye doctor for a retinal exam. Patient again stated that she still suffering from drowsiness. Patient mentioned that it was getting milder now. No treatment medications were reported.  Company comment:This is a spontaneous case concerning a female patient with no reported medical history, who experienced the unexpected serious (medically significant) adverse event of special interests of cardiac flutter among other non-serious events. The event occurred on unknown day after a 5 dose of mRNA-1273.222 vaccine. No information disclosed about diagnostic tests performed or treatments received. At the time of the report, outcome of the event was not recovered. The benefit-risk relationship of mRNA-1273.222 vaccine is not affected by this report.   Reporter did not allow further contact; Sender's Comments: This is a spontaneous case concerning a female patient with no reported medical history, who experienced the unexpected serious (medically significant) adverse event of special interests of cardiac flutter among other non-serious events. The event occurred on unknown day after a 5 dose of mRNA-1273.222 vaccine. No information disclosed about diagnostic tests performed or treatments received. At the time of the report, outcome of the event was not recovered. The benefit-risk relationship of mRNA-1273.222 vaccine is not affected by this report.