EXACERBATION OF MULTIPLE SCLEROSIS AFTER VACCINATION; This spontaneous report was received from literature: This report concerned a 25 year old female. The objective of this study was to explore the relationship of COVID-19 vaccinations with Multiple Sclerosis relapses (MSR). The patient's height, and weight were not reported. The patient's past medical history included: optic neuritis (fully resolved with steroid treatment) and concurrent conditions included: multiple sclerosis and family history positive for MS in her mother and smoking cannabis (cannabis a few times a week (denied nicotine use) and other pre-existing medical conditions included: The patient was not taking any medications at home. A pregnancy test was not done. MS clinically isolated syndrome (CIS) had been diagnosed four years before this presentation when the patient had debuted with an episode of optic neuritis that fully resolved with steroid treatment. The patient previously received covid-19 vaccine ad26.cov2.s (Dose number in series 1) (suspension for injection, route of admin and batch number were not reported, expiry: unknown) dose, start therapy date were not reported (about seven months earlier) administered 1 total, for prophylactic vaccination. It was unknown whether patient had any adverse events following vaccination with first dose of covid-19 vaccine ad26. cov2.s. The patient received additional covid-19 vaccine ad26.cov2.s (Dose number in series 2) (suspension for injection, route of admin, and batch number were not reported, expiry: unknown) dose, start therapy date were not reported, administered 1 total, for prophylactic vaccination. The batch number was not reported and has been requested. Non-company suspect drugs included: medroxyprogesterone acetate one shot of (Depo-Provera) approximately three months before (injection, route of admin, and batch number were not reported) dose, frequency, and therapy dates were not reported for hormonal contraception. Concomitant medications included medroxyprogesterone for hormonal contraception. On an unspecified date, the patient presented with dragging of her left foot when ambulating for five days. She reported that her left lower extremity had begun feeling unstable and stiff when stepping down (exacerbation of multiple sclerosis after vaccination) (Dose number in series 2). On an unspecified date, the patient was hospitalized for unspecified number of days. A review of systems was only positive for mild intermittent paresthesia of the left thumb that had started around the same time as her left foot deficit. Over the next few days, there was no change in symptoms. MRI of brain at that time showed findings consistent with MS and she followed up with a neurologist for a short time but stopped due to not presenting with any further symptoms and was not placed on maintenance therapy. That episode had occurred after she had begun hormonal contraception with intramuscular medroxyprogesterone and because of that she had held off from continuing any form of hormonal contraceptives, until recently before the current episode when she had decided to restart; she had gotten one shot of Depo-Provera (Pfizer Inc) approximately three months before. Vital signs were within normal range, there were no abnormal findings on physical or neurological examination at the bedside. The deficit was only noticeable during gait evaluation, with dragging of the left foot and absent ankle dorsiflexion. On the third day of hospitalization, the patient reported very mild improvement.  Laboratory data (dates unspecified) included: computed tomography of the head without the administration of contrast material (CT scan) (NR: not provided) unremarkable, Comprehensive metabolic panel (NR: not provided) within normal values, Hemogram (NR: not provided) within normal values, Magnetic resonance imaging (MRI brain) (NR: not provided) showed several foci of fluid-attenuated inversion recovery (FLAIR) hyperintensities related to the periventricular white matter, the largest one in the right posterior frontal lobe measuring 1.4 cm and consistent with demyelinating disease, Magnetic resonance imaging (NR: not provided) showed findings consistent with MS, Neurological examination (NR: not provided) no abnormal findings, Nuclear magnetic resonance imaging spinal (NR: not provided) FLAIR hyperintensities, Physical examination (NR: not provided) no abnormal findings and Urinalysis (NR: not provided) within normal values.  Treatment medications (dates unspecified) included: methylprednisolone 1000 mg of intravenous (IV) and neurology consult advised three total doses of IV methylprednisolone sodium succinate (SOLU-MEDROL) (Pfizer Inc) and physical therapy. Physical therapy provided gait training exercises. She was discharged home with a follow-up neurological appointment in one week. The action taken with covid-19 vaccine ad26.cov2.s, and medroxyprogesterone acetate was not applicable. The patient was recovering from exacerbation of multiple sclerosis after vaccination. The authors emphasized on the awareness that must be created among physicians, to be aware of the possibility and to monitor MS patients for relapse following vaccination. Advanced preparation for relapse may aid in a more timely diagnosis and treatment of MSR and ultimately better patient outcomes. Additional research is needed to establish an association between MSR and COVID-19 vaccination. This report was serious (Hospitalization Caused / Prolonged).; Sender's Comments: V0: 20220538340- COVID-19 VACCINE AD26.COV2.S-EXACERBATION OF MULTIPLE SCLEROSIS AFTER VACCINATION. The event(s) has a compatible/suggestive temporal relationship, is unlabeled, and has unknown scientific plausibility. There are other factors more likely to be associated with the event(s) than the drug. Specifically: CONMEDS-OTHER SUSPECT DRUGS. Therefore, this event(s) is considered not related.