Multiple sclerosis pseudo relapse; This literature-non-study case was reported in a literature article and describes the occurrence of MULTIPLE SCLEROSIS PSEUDO RELAPSE (Multiple sclerosis pseudo relapse) in a  patient of an unknown age and gender who received mRNA-1273 (Spikevax) for COVID-19 prophylaxis.       The patient's past medical history included Multiple sclerosis.   On an unknown date, the patient received second dose of mRNA-1273 (Spikevax) (unknown route) 1 dosage form. On an unknown date, received first dose of mRNA-1273 (Spikevax) (unknown route) dosage was changed to 1 dosage form. On an unknown date, the patient experienced MULTIPLE SCLEROSIS PSEUDO RELAPSE (Multiple sclerosis pseudo relapse) (seriousness criterion medically significant). At the time of the report, MULTIPLE SCLEROSIS PSEUDO RELAPSE (Multiple sclerosis pseudo relapse) had resolved.        For mRNA-1273 (Spikevax) (Unknown), the reporter did not provide any causality assessments.  Company comment: This is a literature non-study case concerning a patient of an unknown age (mean age 55.3) and gender with past medical history of Multiple sclerosis., who experienced the serious unexpected medically significant multiple sclerosis pseudo relapse. The event occurred after receiving a dose of mRNA-1273 vaccine (event and vaccine date and dose were not provided). The patient received 2 doses of the mRNA-1273 vaccine. No treatment or concomitant medication was provided. The event was reported as resolved. The benefit-risk relationship of mRNA-1273 vaccine is not affected by this report.   This case belonged to patient number 5 of 8 patients reported.  Concomitant and treatment medications were not reported.  Author retrospectively identified 250 Multiple sclerosis (MS) patients at institution who had received the initial vaccination cycle of the currently approved COVID-19 vaccines in the country. 151 of these patients also received a booster dose. side effects (SE) attributed to the COVID-19 vaccinations during a 90- day post-vaccination observation period were collected as part of the standard clinical care.  88 Multiple sclerosis (MS) patients received the first and second doses of the mRNA-1273 vaccine. There were 2 cases of pseudo-relapse after the first mRNA-1273 dose and 4 cases following the second mRNA-1273 dose. Symptoms mainly consisted of weakness and severe fatigue.   Most patients reporting a pseudo-relapse returned to baseline within less than 96 hours except for 2 cases that lasted for 1-2 weeks. There was no permanent neurological disability or severe, life-threatening adverse events reported. No treatment was recommended or performed during any of our pseudo-relapse cases. No acute cases of MS relapse were noted in our studied population that could be confirmed by clinical or radiological findings.  Author concluded that COVID-19 vaccination is safe in patients with MS with a comparable side effects (SE) spectrum to the general population. The risk for clinical relapses was absent in our cohort. Cases of temporary worsening of MS symptoms following SARS-CoV-2 are rare. Our findings support those reported by other recent studies and the CDC recommendation for MS patients to receive the FDA-approved COVID-19 vaccines, including the boosters.    This case was linked to US-MODERNATX, INC.-MOD-2023-732774 (Linked Report).   Most recent FOLLOW-UP information incorporated above includes: On 11-Jul-2023: Live follow-up received by safety on 12-Jul-2023 has an email with full text article and contains significant information: Reporter information, literature information, medical history, suspect details, and event details were updated.; Sender's Comments: Company comment: This is a literature non-study case concerning a patient of an unknown age (mean age 55.3) and gender with past medical history of Multiple sclerosis., who experienced the serious unexpected medically significant multiple sclerosis pseudo relapse. The event occurred after receiving a dose of mRNA-1273 vaccine (event and vaccine date and dose were not provided). The patient received 2 doses of the mRNA-1273 vaccine. No treatment or concomitant medication was provided. The event was reported as resolved. The benefit-risk relationship of mRNA-1273 vaccine is not affected by this report. US-MODERNATX, INC.-MOD-2023-732774:Master Case