probable hepatitis A vaccine unmasking of RRMS; spinal motor attack; prior spinal CIS; This serious case was reported in a literature article and described the occurrence of relapsing-remitting multiple sclerosis in a adult patient who received Hepatitis A vaccine for prophylaxis.   Co-suspect products included tetanus vaccine for prophylaxis.   Concurrent medical conditions included graves' disease. Additional patient notes included no cancer.   On an unknown date, the patient received Hepatitis A vaccine and tetanus vaccine. On an unknown date, 7 days after receiving Hepatitis A vaccine, the patient experienced relapsing-remitting multiple sclerosis (Verbatim: probable hepatitis A vaccine unmasking of RRMS) (serious criteria GSK medically significant), sensorimotor disorder (Verbatim: spinal motor attack) and clinically isolated syndrome (Verbatim: prior spinal CIS) (serious criteria GSK medically significant). The patient was treated with methylprednisolone. The outcome of the relapsing-remitting multiple sclerosis, sensorimotor disorder and clinically isolated syndrome were not resolved.   The reporter considered the relapsing-remitting multiple sclerosis, sensorimotor disorder and clinically isolated syndrome to be probably related to Hepatitis A vaccine.     The company considered the relapsing-remitting multiple sclerosis, sensorimotor disorder and clinically isolated syndrome to be probably related to Hepatitis A vaccine.   Additional Information: GSK Receipt Date: 30-MAR-2023 Co-suspect included meningococcal vaccine. This case corresponds to the patient 23 reported in literature article. The patient was a part of study which aimed to expand the literature on biologic- and vaccine-associated central nervous system (CNS) inflammation by examining the prevalence and clinical characteristics of iatrogenic CNS demyelinating and inflammatory events in patients referred to the neuroimmunology clinic over the past five years. Adult patients seen over five years (January 2017 to December 2021) at the tertiary neuroimmunology clinic were evaluated for potential iatrogenic demyelinating and inflammatory events secondary to tumor-necrosis-factor-alpha inhibitors (TNFAIs), immune-checkpoint inhibitors (ICIs), vaccines, and/or other immunomodulators. In patients with suspected iatrogenic CNS inflammation, the Adverse Drug Reaction Probability Scale was used to calculate a score indicating the probability of drug- or vaccine induced adverse events. The scale consists of 10 questions answered as "Yes," "No," or "Do not know," with different points (-1, 0, +1, or + 2) assigned to each. Depending on the patient's score, the iatrogenic event was labeled as definite (more than or equal to 9), probable (5-8), possible (2-4), or doubtful (less than or equal to 1). Potential iatrogenic events occurring more than one year after TNFAI, ICI, or vaccine exposure were included in the original analysis. However, these events were scored lower on the scale as they yielded an answer of "yes", which assesses the possibility of alternative explanations for the adverse reaction. A total of 422 patients seen at the neuroimmunology clinic for confirmed immune-mediated CNS disorders were screened for a potential iatrogenic etiology related to TNFAIs, ICIs, vaccinations, and/or other immunomodulators. In total, 27 potential iatrogenic events in 27 patients were observed accounting for 6.4% of all new referrals to the neuroimmunology clinic over the five-year period.  The patient was in early 40s at the time of neurological presentation. The patient other immune diseases included Grave's disease. The patient received Hepatitis A, Meningococcal and Tetanus vaccine and after 7 days presented with spinal motor attack. The patient's iatrogenic diagnosis was reported as probable meningococcal, Hepatitis A and tetanus vaccine unmasking of Relapsing-remitting multiple sclerosis (RRMS). The score was reported as 7.  The final disease course was RR (prior spinal clinically isolated syndrome (CIS). Cancer was not detected at the time of presentation.The patient had no response to corticosteroids and/or immunotherapy. The influenza vaccine was most-frequently implicated in our vaccine-related events followed by COVID-19 mRNA vaccines and the tetanus vaccine. Vaccine-related events were more likely to resolve spontaneously than TNFAI- or ICI-related events, suggesting that vaccines may result in milder disease severity compared to other triggers. This article corresponding to this case is not available for regulatory reporting due to copyright restriction.; Sender's Comments:  US-GSK-US2023GSK048173: