tremors while awake & sleeping; not being able to sleep good at night; after medication feeling extremely tired and unable to work; after medication feeling extremely tired and unable to work; seizures/seizures behaviors/multiple seizures while awake & sleeping; This spontaneous case was reported by a consumer and describes the occurrence of SEIZURE (seizures/seizures behaviors/multiple seizures while awake & sleeping) in a 48-year-old female patient who received mRNA-1273 (Spikevax) (batch no. 048l21a) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.  The patient's past medical history included Seizure and Neurological symptoms NOS. Concurrent medical conditions included Autoimmune disorder (preexisting clinical condition Voltage-Gated Potassium Channel Antibody Disorder, extremely rare that was diagnosed when patient was going through breast cancer and when patient also had a seizure at that time "similar to what she was experiencing"), Breast cancer female (she had treatment and surgery) since January 2015 and Allergy to antibiotic (amoxicillin). Concomitant products included LEVOTHYROXINE SODIUM (SYNTHROID) and HYDROCHLOROTHIAZIDE, LISINOPRIL (LISINOPRIL AND HYDROCHLOROTHIAZIDE) for an unknown indication.  On 26-Mar-2022 at 3:00 PM, the patient received first dose of mRNA-1273 (Spikevax) (unknown route) 1 dosage form. On 27-Mar-2022 at 10:00 PM, the patient experienced SEIZURE (seizures/seizures behaviors/multiple seizures while awake & sleeping) (seriousness criterion medically significant). On an unknown date, the patient experienced TREMOR (tremors while awake & sleeping), INSOMNIA (not being able to sleep good at night), IMPAIRED WORK ABILITY (after medication feeling extremely tired and unable to work) and FATIGUE (after medication feeling extremely tired and unable to work). The patient was treated with LEVETIRACETAM DIHYDROCHLORIDE (KEPPRA [LEVETIRACETAM DIHYDROCHLORIDE]) for Seizures, at a dose of 1000 milligram twice a day and LORAZEPAM for Seizures, at a dose of .5 milligram twice a day. At the time of the report, SEIZURE (seizures/seizures behaviors/multiple seizures while awake & sleeping) was resolving and TREMOR (tremors while awake & sleeping), INSOMNIA (not being able to sleep good at night), IMPAIRED WORK ABILITY (after medication feeling extremely tired and unable to work) and FATIGUE (after medication feeling extremely tired and unable to work) had not resolved.  DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): In December 2021, SARS-CoV-2 antibody test: positive (Positive) positive, right after Christmas.  The action taken with mRNA-1273 (Spikevax) (Unknown) was unknown.  Following vaccination, the next day at 10 pm patient started to experience seizures, went to ER, seizures behaviors, in ER received 2 seizures meds but then was released to come home after 6 hours as the facility did not had the structure to admit patient for longer treatment, multiple seizures and tremors while awake and sleeping, not being able to sleep good at night, after medication feeling extremely tired and unable to work. HCP told that it was patient's body way to react to the vaccination in combination with patients preexisting clinical condition VGKC antibody disorder. Treatment medication reported as Potassium HCL 20mcg twice daily. The symptoms improved with administration with medication "much lessen with lorazepam". It was reported that medication had helped but symptoms were still there and if they retire the medication symptoms would come back. Patient did not receive any other vaccines, it was patients first vaccine she received since cancer. On 30-Jun-2022, patient had schedule an appointment for in house visit.  Company Comment: This is a Spontaneous case concerning a 48-year-old female patient, with relevant medical history of seizure, neurological symptoms, autoimmune disorder, and breast cancer, who experienced the unexpected, serious (medically significant), and AESI of Seizure. The event occurred 1 day after the first dose of mRNA-1273 vaccine. Patient was admitted to ER for 6 hours due to seizures. She received treatment with levetiracetam and lorazepam and then was released, as ER didn´t have the structure to admit her for longer treatment. Patient experienced multiple seizures and tremors, not being able to sleep good at night. After medication she felt extremely tired and unable to work. Medical history of seizure, neurological symptoms, autoimmune disorder, and breast cancer, remain confounders for the events. The benefit-risk relationship of mRNA-1273 vaccine is not affected by this report.; Sender's Comments: This is a Spontaneous case concerning a 48-year-old female patient, with relevant medical history of seizure, neurological symptoms, autoimmune disorder, and breast cancer, who experienced the unexpected, serious (medically significant), and AESI of Seizure. The event occurred 1 day after the first dose of mRNA-1273 vaccine. Patient was admitted to ER for 6 hours due to seizures. She received treatment with levetiracetam and lorazepam and then was released, as ER didn´t have the structure to admit her for longer treatment. Patient experienced multiple seizures and tremors, not being able to sleep good at night. After medication she felt extremely tired and unable to work. Medical history of seizure, neurological symptoms, autoimmune disorder, and breast cancer, remain confounders for the events. The benefit-risk relationship of mRNA-1273 vaccine is not affected by this report.