A 43-year-old, female with a history of Multiple Sclerosis (MS), was enrolled in a study: Booster Effects with Autoimmune Treatments in Patients with Poor Response to Initial COVID-19 Vaccine.  On 02Mar2021, the participant received her first dose of mRNA Moderna COVID-19 vaccine and she received her second dose on 29Mar2021. On 11Oct2021, the participant signed the informed consent form. Sample collection on 11Oct2021 confirmed the study participant had a negative serologic response to initial vaccination (Anti-SARS-CoV-2 S (RBD) result = 0.4 U/mL). The participant was enrolled into Cohort C ? B cell depletion therapy (last dose of ocrelizumab was received on 16Dec2020), and received the booster on 04Nov2021. The participant?s underlying autoimmune disease is MS. No action taken with the vaccination and the participant remains in the study. On 04Nov2021 at site visit, the participant received the mRNA Moderna COVID booster. She complained of headaches and chills, had a low-grade fever, and did not feel well. She took 2 Motrin PM tablets before going to bed.  On 05Nov2021, she got up at 4:30 am with muscle spasms and had trouble getting out of bed. She had worsened urinary incontinence (participant has a history of urinary incontinence and wears Depends as she has a few episodes a week). The participant tried to get up from the bed but fell. She was unable to get herself back into the bed and her daughter called paramedics and got her back to the bed. She decided not to go to emergency room (ER). Over the course of the day, she was unable to walk and felt that her limbs were not working. She complained of body pain and she called paramedics again around 4:30 pm. The participant presented to an outside ER between 5:30 ? 6:00 pm with increased weakness and urinary incontinence. Magnetic Resonance Imaging (MRI) of the head and spine did not show active or new MS lesions. Chest x-ray completed, which revealed no lung consolidation, no pleural effusion, no pneumothorax, no cardiomegaly, bones/joints unremarkable, and no acute findings. There was no electromyography (EMG) completed, as the course does not sugesst Guillain-Barré syndrome (GBS) or peripheral neuropathy issues. Complete blood count (CBC) with differential, basic metabolic panel, point-of-care-testing (POCT), SARS-COV-2, and urinalysis with microscopic, no culture was completed. She received 3 doses 500mg of intravenous Solu-Medrol.   On 08Nov2021, the principal investigator (PI) talked to her and she was still in the hospital. She was able to stand up but weakness and shakiness of the arms and legs continued. She was catheterized for her urinary incontinence and not mobile. There was no stool incontinence. She reported feeling 50% of her normal well-being. The participant reported she had a pseudo MS flare which is very common, as her MRIs were normal. Her local neurologist also thought this was a pseudo flare and in the past the participant has had those. Her COVID Polymerase Chain Reaction (PCR) test was negative.   On 10Nov2021, the subject was discharged from the hospital to a rehabilitation center where they noted her cloudy urine which was tested on 13Nov2021 and showed trace protein 3+ LE culture positive for proteus. On 14Nov2021, she began treatment with oral Keflex (cephalexin) for urinary tract infection (UTI).  On 15Nov2021, CBC results revealed white blood cell count 10.8 k/uL, red blood cell count 4.63 m/uL, hemoglobin 13.3 g/dL, hematocrit 40.1%, and platelet count 248 k/uL. Labs were obtained due to mildly elevated liver function tests (LFTs) less than 2 fold. An ultrasound of the liver showed gallstones (not causing pain or other symptoms). The LFTs remained stable. The participant started walking.     On 17Nov2021, an MRI of the spine was performed and did not reveal any new lesions, and is consistent with a pseudo-flare. That same day, the subject completed the Keflex for treating her UTI.   The participant is not back to her baseline as of 22Nov2021 but improving daily and is 80% better. She walked approximately 24 feet with parallel bars. She does not always end up in rehab, but stated ?she wish she had as she is getting stronger than her baseline with rehab?. Her baseline expanded disability status scale (EDSS) was 6.5 walking with walker around her house. A formal EDSS was not obtained at outside rehab.  On 09Dec2021, the participant was discharged from the rehab facility, as the rehabilitation facility feels she has potential to be better than before. The site has asked the facility to fax all relevant labs.