PARALYSIS ON LEFT SIDE; NO FEELING OR STRENGTH IN LEFT SIDE; BLOOD CLOT IN THE BRAIN; CONFUSION; SLURRED SPEECH; UNSTEADY WALKING; FEELS DIZZY; NO ENERGY FOR ANYTHING; AGITATION; LOSS OF HEARING IN LEFT EAR; This spontaneous report received from a patient and her husband and concerned a 45-year-old female patient. Initial information received on 07-JUN-2021 was processed together with additional information received via 2 telephone calls to and from the patient's husband on 11-JUN-2021. The patient's height and weight were not reported. No past medical history or concurrent conditions were reported. The patient had no family history of any blood/clotting disorders and that she did not travel anywhere prior to receiving the vaccine. The patient received COVID-19 vaccine Ad26.CoV2.S (suspension for injection, route of administration not reported, batch number unknown), dose not reported, administered once in total on 13-MAY-2021 for prophylactic vaccination. The batch number was not reported and has been requested. On an unspecified date, the patient experienced feeling dizzy, and had no energy for anything. On 14-MAY-2021, the patient started feeling confused, her mouth started feeling like it was drawing, and her speech started slurring. On 28-MAY-2021 she went to bed and got up and she couldn't feel her left side, with paralysis. She was also drooling and her husband took her to the hospital. The patient was flown by helicopter to another hospital. During the telephone call to the reporter, he reported that his wife's laboratory results were all within normal ranges at the second hospital, including her platelet count at 189,000 (units and normal range not reported). On 29-MAY-2021, a magnetic resonance imaging (MRI) scan of her brain revealed a 12 mm blood clot in the thalamus. The patient was treated with Aspirin (acetylsalicylic acid) and Plavix (clopidogrel bisulfate). It was reported that the clot could not be cleared before she was discharged after 4 days hospitalization on 31-MAY-2021.  As of 07-JUN-2021, the patient reported being highly agitated and could not hear out of her left ear, had no feeling or strength on her left side and was very unsteady walking. As of 11-JUN-2021, the patient's husband reported that the patient was still experiencing weakness of the left side of her body with no energy for anything (reported as being very active prior to vaccination), trouble walking, feeling dizzy sometimes, trouble hearing with her left ear, was very agitated and was frustrated that these events had happened to her. The patient was on medical leave from work at the time of reporting. The action taken with COVID-19 vaccine Ad26.CoV2.S was not applicable. The patient had not recovered from the events.  This report was serious (life-threatening, disability or permanent damage, caused/prolonged hospitalization and other medically important condition).; Sender's Comments: V0: This spontaneous report received from a patient and her husband concerned a 45-year-old woman who experienced blood clot in the thalamus 15 days after vaccine. No past medical history or concurrent conditions were reported. The patient had no family history of any blood/clotting disorders and that she did not travel anywhere prior to receiving the vaccine. On day 15, the patient went to bed and got up and she couldn't feel her left side, with paralysis. She was also drooling and her husband took her to the hospital. The patient was flown by helicopter to another hospital. During the telephone call to the reporter, he reported that his wife's laboratory results were all within normal ranges at the second hospital, including her platelet count at (189,000). On day 16, a magnetic resonance imaging (MRI) scan of her brain revealed a 12 mm blood clot in the thalamus. The patient was treated with aspirin and clopidogrel. It was reported that the clot could not be cleared before she was discharged after 4 days. As of day 25, the patient reported being highly agitated and could not hear out of her left ear, had no feeling or strength on her left side and was very unsteady walking. As of day 29, the patient's husband reported that the patient was still experiencing weakness of the left side of her body with no energy for anything, trouble walking, feeling dizzy sometimes, trouble hearing with her left ear, was very agitated and was frustrated that these events had happened to her. The patient was on medical leave from work at the time of reporting. The occurrence of blood clot in the thalamus could represent background incidence of such events in the general population and the normal platelet count exclude thrombosis with thrombocytopenia syndrome. However, a relationship with Janssen Covid-19 vaccine cannot be ruled out and thus the relationship is considered indeterminate.