SEVERE VIOLENT SEIZURES; VERY HIGH FEVER; THROWING UP; This spontaneous report received from a patient concerned a 39 year old female. The patient's height, and weight were not reported. The patient's concurrent conditions included: pseudo seizure (stress and anxiety seizure) and medicated since diagnosis (mid 2017) regularly, chronic asthma (medicated), depression (medicated), post-traumatic stress (medicated), chronic anxiety (medicated), antibiotic allergy, penicillin allergy, sulfa drugs allergy, food allergy, environmental allergies, non smoker, and non alcohol user, and other pre-existing medical conditions included: The patient had no history of drug abuse or illicit drug usage.  The patient thought pseudo seizures were under control, had not had any for a while. When asked for clarification, patient stated she truly do not know seizure duration, she blacked out. The patient was not pregnant at the time of reporting. The patient experienced drug allergy when treated with codeine for drug used for unknown indication.  The patient received covid-19 vaccine ad26.cov2.s (suspension for injection, route of admin not reported, batch number: 1808978, and expiry: UNKNOWN) dose was not reported, 1 total, administered on 27-MAR-2021 for prophylactic vaccination into left arm (not 100 percent sure). No concomitant medications were reported. On 28-MAR-2021, the patient was in seizures, very high fever (high enough to be throwing up), just started into convulsion with seizures, fever spiked way up and could not come out of seizure, kept shaking and shaking, it was extremely violent. The patient stated that she wanted to throw up but could not because it stayed in her mouth (she was sitting up). Got help to get up but ended up on the floor convulsing and vomit it got everywhere. The patient stated that she thought when she was convulsing, she ended up injuring her hips and back, head, legs and possibly other parts of the body. The patient's father reported that patient started one after another, continued seizing. Real hard time. Started throwing up. They had a real mess. It went on all night long to the next day. On 29-MAR-2021, the patient's father stated that she stated to calm down and have less seizures. The father had to stay up all night with her. On 30-MAR-2021 (afternoon), seizures did not come quite as often. The father reported that the seizure would last 10 minutes. Fever was 102 F or something like that. The father briefly did called the hospital and told them what was going on and they said to give patient seizure medicine and just watch patient to saw if that helps any. The patient stated that she told her back then physician and the new one she has now too about the seizures after vaccination. The action taken with covid-19 vaccine ad26.cov2.s was not applicable. The patient recovered from very high fever, and throwing up on 29-MAR-2021, and was recovering from severe violent seizures. This report was serious (Other Medically Important Condition).; Sender's Comments: V0: 20211032227-COVID-19 VACCINE AD26.COV2.S-Severe violent seizures. This event is considered unassessable. The event has a compatible/suggestive temporal relationship, is unlabeled, and has unknown scientific plausibility. There is no information on any other factors potentially associated with the event.