Felt her heart was fluttering a little bit, like when you have anxiety; Felt like she could not breath, but O2 stats were ok; Felt her throat was tightening up; Within a minute of vaccination, patient turned bright red all over the body/ Lobster red, including ears; Feet tingling; Feet went numb; Left a little bit dizzy/ Felt like she was going to implode; Injection site arm was swollen but not red/ Arm is a little swollen; This spontaneous case was reported by a nurse and describes the occurrence of CARDIAC FLUTTER (Felt her heart was fluttering a little bit, like when you have anxiety), DYSPNOEA (Felt like she could not breath, but O2 stats were ok), THROAT TIGHTNESS (Felt her throat was tightening up) and ERYTHEMA (Within a minute of vaccination, patient turned bright red all over the body/ Lobster red, including ears) in a 33-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch no. 067H21A) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.     No Medical History information was reported.    On 03-Feb-2022, the patient received third dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) .25 milliliter. On 03-Feb-2022, the patient experienced CARDIAC FLUTTER (Felt her heart was fluttering a little bit, like when you have anxiety) (seriousness criterion medically significant), DYSPNOEA (Felt like she could not breath, but O2 stats were ok) (seriousness criterion medically significant), THROAT TIGHTNESS (Felt her throat was tightening up) (seriousness criterion medically significant), ERYTHEMA (Within a minute of vaccination, patient turned bright red all over the body/ Lobster red, including ears) (seriousness criterion medically significant), PARAESTHESIA (Feet tingling), HYPOAESTHESIA (Feet went numb), DIZZINESS (Left a little bit dizzy/ Felt like she was going to implode) and VACCINATION SITE SWELLING (Injection site arm was swollen but not red/ Arm is a little swollen). On 03-Feb-2022, ERYTHEMA (Within a minute of vaccination, patient turned bright red all over the body/ Lobster red, including ears) had resolved. At the time of the report, CARDIAC FLUTTER (Felt her heart was fluttering a little bit, like when you have anxiety) and VACCINATION SITE SWELLING (Injection site arm was swollen but not red/ Arm is a little swollen) had not resolved and DYSPNOEA (Felt like she could not breath, but O2 stats were ok), THROAT TIGHTNESS (Felt her throat was tightening up), PARAESTHESIA (Feet tingling), HYPOAESTHESIA (Feet went numb) and DIZZINESS (Left a little bit dizzy/ Felt like she was going to implode) was resolving.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On 03-Feb-2002, Blood pressure measurement: 151/85 (Inconclusive) Blood pressure was 151/85. On 03-Feb-2002, Heart rate: 73 (Inconclusive) Pulse was 73. On 03-Feb-2002, Oxygen saturation: stats were ok (normal) Stats were ok.     For mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown), the reporter did not provide any causality assessments.   No health conditions or concomitant medication was reported.  Within a minute of booster vaccination, patient turned bright red all over the body- lobster red, including ears. Patient felt like she could not breath, but O2 stats were ok. Patient felt like throat was tightening up and like she was going to implode. Patient's feet went numb and tingling. By the time they got the EpiPen, patient started to look a little better and feel better and the patient refused the EpiPen. As fast as it seemed to come on, it left just as fast. It left patient's ears bright red. After 30 minutes, patient was pretty much recovered, but injection site arm was swollen, but not red. Patient left a little bit dizzy. After 30 minutes, patient was feeling much better and went home.  Company Comment - This regulatory authority case concerns a 33 year old female patient with no relevant medical history, who experienced the serious unexpected events of cardiac flutter, dyspnoea, throat tightness and erythema. The event occurred on the same day, within a minute of vaccination, after the third dose of mRNA-1273 vaccine,. events spontaneously resolved 30 minutes later. The rechallenge was not applicable as there are no plans for future dosing. The benefit-risk relationship of the mRNA-1273 vaccine is not affected by this report.  On 04-Feb-2022, HCP checked on patient, arm was a little swollen. Patient felt her heart was fluttering a little bit, like when you have anxiety.; Sender's Comments: This regulatory authority case concerns a 33 year old female patient with no relevant medical history, who experienced the serious unexpected events of cardiac flutter, dyspnoea, throat tightness and erythema. The event occurred on the same day, within a minute of vaccination, after the third dose of mRNA-1273 vaccine,. events spontaneously resolved 30 minutes later. The rechallenge was not applicable as there are no plans for future dosing. The benefit-risk relationship of the mRNA-1273 vaccine is not affected by this report.