tiredness; a bit of headache; seizures; minor difficulty breathing; tightness on his chest; patient felt nauseous; patient started to experience shaking, like it was freezing; Previously administered products Pfizer for 3 doses; This spontaneous case was reported by a consumer and describes the occurrence of SEIZURE (seizures) in a 76-year-old male patient who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.     Previously administered products included for Product used for unknown indication: Pfizer (2nd Dose) in April 2021, Pfizer (1st Dose) in 2021, Pfizer (3rd Dose and 1st Booster) in August 2021. Past adverse reactions to the above products included No adverse event with Pfizer, Pfizer and Pfizer. Concurrent medical conditions included Blood pressure high (Patient was under regular medications for high blood pressure but he did not remember the names. It started 10 years ago. No recent change in status.) since 2012, Cholesterol (Patient was under regular medications for cholesterol but he did not remember the names. It started 10 years ago. No recent change in status.) since 2012, Asthma (It started 15 to 20 years ago, no recent change in status.), Hypersensitivity, Drug hypersensitivity and Drug hypersensitivity.    On 07-May-2022, the patient received fourth dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) 1 dosage form. On 07-May-2022, the patient experienced TREMOR (patient started to experience shaking, like it was freezing) and INTERCHANGE OF VACCINE PRODUCTS (Previously administered products Pfizer for 3 doses). On 08-May-2022, the patient experienced SEIZURE (seizures) (seriousness criterion medically significant), DYSPNOEA (minor difficulty breathing), CHEST DISCOMFORT (tightness on his chest) and NAUSEA (patient felt nauseous). On 09-May-2022, the patient experienced FATIGUE (tiredness) and HEADACHE (a bit of headache). The patient was treated with PARACETAMOL (TYLENOL) for Adverse event, at a dose of 1 dosage form. On 07-May-2022, TREMOR (patient started to experience shaking, like it was freezing) had resolved. On 08-May-2022, SEIZURE (seizures), DYSPNOEA (minor difficulty breathing), CHEST DISCOMFORT (tightness on his chest) and NAUSEA (patient felt nauseous) had resolved. At the time of the report, FATIGUE (tiredness) and HEADACHE (a bit of headache) was resolving and INTERCHANGE OF VACCINE PRODUCTS (Previously administered products Pfizer for 3 doses) outcome was unknown.            Patient had taken first 3 doses of Pfizer vaccine in 2021, April 2021 and August 2021 respectively. His 2nd booster was Moderna taken on 7th may 2022. 5 hours after his Moderna booster patient experienced shaking like he was freezing, for which he took Tylenol and went to bed. Later at 4 am  he experienced seizures, felt minor difficulty in breathing and tightness in chest. He considered going to the ER but later decided to stay at home, so no lab tests was reported. On 8th May he felt nauseous and on 9th may he felt minor complications like headache and tiredness. Patient was taking regular medications for high BP and Cholesterol , he did not remember the name. Patient said he had a previous reaction to Pfizer vaccine but not to this extent. Patient had not had a COVID-19 positive test or diagnosis. Patient had no history of Myocarditis/ Pericarditis. Concomitant medication was not reported.  Company Comment: This spontaneous case reported by consumer concerns a 76-year-old male patient, with no relevant medical history, who experienced unexpected, serious (medically significant) event seizure, 1 day after receiving a booster dose of mRNA-1273 (fourth dose in a Covid19 vaccination schedule).  Around 5 hours after vaccination, he had shaking for which he took Paracetamol.  The next day he had seizure with minor dyspnea, chest tightness and nausea.  He considered going to the emergency room but later opted to stay home, hence no labs reported.  The seizure had resolved.  Additionally, it is noted that the patient previously received 3 doses of a different Covid19 vaccine Pfizer (interchange of vaccine products).  The benefit risk relationship of mRNA-1273 is not affected by this report.; Sender's Comments: This spontaneous case reported by consumer concerns a 76-year-old male patient, with no relevant medical history, who experienced unexpected, serious (medically significant) event seizure, 1 day after receiving a booster dose of mRNA-1273 (fourth dose in a Covid19 vaccination schedule).  Around 5 hours after vaccination, he had shaking for which he took Paracetamol.  The next day he had seizure with minor dyspnea, chest tightness and nausea.  He considered going to the emergency room but later opted to stay home, hence no labs reported.  The seizure had resolved.  Additionally, it is noted that the patient previously received 3 doses of a different Covid19 vaccine Pfizer (interchange of vaccine products).  The benefit risk relationship of mRNA-1273 is not affected by this report.