I had 3 seizures after the vaccine within 6 hours of the booster shot; Interchange of vaccine products; This spontaneous case was reported by a patient and describes the occurrence of SEIZURE (I had 3 seizures after the vaccine within 6 hours of the booster shot) in a 54-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch no. 066H21A) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.     The patient's past medical history included Epilepsy and Lupus syndrome. Previously administered products included for Product used for unknown indication: janssen on 21-Apr-2021. Past adverse reactions to the above products included No adverse event with janssen. Concomitant products included PREDNISOLONE, LEVOTHYROXINE SODIUM (SYNTHROID), CLOPIDOGREL BISULFATE (PLAVIX), VERAPAMIL and IBUPROFEN for an unknown indication.    On 27-Dec-2021, the patient received third dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On 27-Dec-2021, the patient experienced SEIZURE (I had 3 seizures after the vaccine within 6 hours of the booster shot) (seriousness criterion medically significant). 27-Dec-2021, the patient experienced INTERCHANGE OF VACCINE PRODUCTS (Interchange of vaccine products). The patient was treated with LORAZEPAM in December 2021 for Seizure, at an unspecified dose and frequency. On 27-Dec-2021, INTERCHANGE OF VACCINE PRODUCTS (Interchange of vaccine products) had resolved. At the time of the report, SEIZURE (I had 3 seizures after the vaccine within 6 hours of the booster shot) outcome was unknown.        For mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown), the reporter did not provide any causality assessments.   Company comment: This spontaneous case concerns a 54-year-old female patient with a relevant medical history of Epilepsy and Systemic lupus erythematosus, who experienced the  unexpected serious (medically significant) event of Seizure after mRNA- 1273 vaccine, booster dose of the vaccination schedule. Interchange of vaccines products occurred since the patient had received initial schedule of vaccination with Janssen COVID-19 Vaccine. The events occurred on the day after the booster dose of mRNA- 1273 vaccine. The patient experienced 3 seizures after the vaccine within 6 hours of the booster shot. Very limited information is available regarding baseline health condition before vaccination, diagnostic work-up and other potential precipitating factors.  Previous history of Epilepsy and Systemic lupus erythematous remain as confounder. The benefit-risk relationship of mRNA- 1273 vaccine is not affected by this report.; Sender's Comments: This spontaneous case concerns a 54-year-old female patient with a relevant medical history of Epilepsy and Systemic lupus erythematosus, who experienced the  unexpected serious (medically significant) event of Seizure after mRNA- 1273 vaccine, booster dose of the vaccination schedule. Interchange of vaccines products occurred since the patient had received initial schedule of vaccination with Janssen COVID-19 Vaccine. The events occurred on the day after the booster dose of mRNA- 1273 vaccine. The patient experienced 3 seizures after the vaccine within 6 hours of the booster shot. Very limited information is available regarding baseline health condition before vaccination, diagnostic work-up and other potential precipitating factors.  Previous history of Epilepsy and Systemic lupus erythematous remain as confounder. The benefit-risk relationship of mRNA- 1273 vaccine is not affected by this report.