RRMS/ RR (initial relapse); This literature case was received on 14-Mar-2023, reported by other healthcare professional and concerned an adult patient in late 60s, of an unreported gender.   This study objective was to evaluate the prevalence and clinical characteristics of iatrogenic central nervous system (CNS) inflammation in a tertiary neuroimmunology clinic since various vaccines, tumor-necrosis-factor-alpha inhibitors (TNFAIs), immune-checkpoint inhibitors (ICIs), and other immunomodulators had been linked to inflammatory CNS events. However, the prevalence of iatrogenic events in the neuroimmunology clinic was unknown.  The patient's medical history and concomitant medications were not reported.  As reported, the patient had no other autoimmune disease or cancer.   On an unspecified date, the patient was vaccinated with influenza vaccine (brand not specified; dose, route of administration, anatomical location and indication: not reported). The batch number was not reported.  On an unspecified date, two and a half months after receiving influenza vaccine, the patient experienced spinal sensory attack.  On an unspecified date, the patient was seen at the tertiary neuroimmunology clinic where iatrogenic diagnosis of probable flu vaccine unmasking of relapsing-remitting multiple sclerosis (RRMS) was set, and final disease course was reported as RR initial relapse.  On an unspecified date, the patient recovered from the event. It was reported as spontaneous recovery.   The reporter assessed the event of 'relapsing-remitting multiple sclerosis' to be probably related to influenza vaccine. Iatrogenic diagnosis was reported as probable flu vaccine unmasking of relapsing-remitting multiple sclerosis (RRMS).  The event of 'relapsing-remitting multiple sclerosis' was considered to be medically significant by a Physician within Seqirus's Pharmacovigilance and Risk Management Department.  In conclusion of this study in was stated that iatrogenic CNS inflammation was rare and typically involved steroid-responsive monophasic events. A subset of iatrogenic events could unmask or worsen relapsing disorders. The probability of iatrogenicity was higher in vaccine and immune-checkpoint inhibitors (ICI)-related events compared to TNFAIs- related events.    This case is linked with cases 202301977, 20230978 and 202301986 (the same literature article).  Company comment: This study objective was to evaluate the prevalence and clinical characteristics of iatrogenic central nervous system inflammation in a tertiary neuroimmunology clinic since various vaccines, tumor-necrosis-factor-alpha inhibitors, immune-checkpoint inhibitors, and other immunomodulators had been linked to inflammatory CNS events. An adult patient in late 60s experienced spinal sensory attack two and a half months after receiving the suspect product influenza vaccine. Thereafter, the patient was seen at the tertiary neuroimmunology clinic where iatrogenic diagnosis of probable flu vaccine unmasking of relapsing-remitting multiple sclerosis was set, and final disease course was reported as RR initial relapse. The patient's medical history and concomitant drugs were not provided. Reportedly, the patient had no other autoimmune disease or cancer. Based on available information causality between suspect vaccine and the reported event is assessed as possibly related.; Reporter's Comments: Iatrogenic diagnosis was reported as probable flu vaccine unmasking of relapsing-remitting multiple sclerosis (RRMS).; Sender's Comments: This study objective was to evaluate the prevalence and clinical characteristics of iatrogenic central nervous system inflammation in a tertiary neuroimmunology clinic since various vaccines, tumor-necrosis-factor-alpha inhibitors, immune-checkpoint inhibitors, and other immunomodulators had been linked to inflammatory CNS events. An adult patient in late 60s experienced spinal sensory attack two and a half months after receiving the suspect product influenza vaccine. Thereafter, the patient was seen at the tertiary neuroimmunology clinic where iatrogenic diagnosis of probable flu vaccine unmasking of relapsing-remitting multiple sclerosis was set, and final disease course was reported as RR initial relapse. The patient's medical history and concomitant drugs were not provided. Reportedly, the patient had no other autoimmune disease or cancer. Based on available information causality between suspect vaccine and the reported event is assessed as possibly related.