Guillain-Barre Syndrome; diarrhea/abdominal pain/fevers/fatigue; This literature-non-study case was reported in a literature article and describes the occurrence of GUILLAIN-BARRE SYNDROME (Guillain-Barre Syndrome) in a 50-year-old male patient who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 prophylaxis. The occurrence of additional non-serious events is detailed below.   LITERATURE REFERENCE:      No Medical History information was reported.    On an unknown date, the patient received third dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On an unknown date, the patient experienced GUILLAIN-BARRE SYNDROME (Guillain-Barre Syndrome) (seriousness criteria hospitalization and medically significant) and DIARRHOEA (diarrhea/abdominal pain/fevers/fatigue). The patient was treated with IMMUNOGLOBULINS NOS (IMMUNOGLOBULIN I.V) (intravenous) at an unspecified dose and frequency and IMMUNOGLOBULINS NOS (IMMUNOGLOBULIN I.V) (intravenous) at an unspecified dose and frequency. At the time of the report, GUILLAIN-BARRE SYNDROME (Guillain-Barre Syndrome) outcome was unknown and DIARRHOEA (diarrhea/abdominal pain/fevers/fatigue) had resolved.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On an unknown date, Computerised tomogram head: showed a C1/C2 subluxation possibly chronic without significant focal soft tissue swelling. On an unknown date, Computerised tomogram spine: showed C1-C2 subluxation, possibly chronic.. On an unknown date, Culture stool: (Negative) were collected for C.Jejuni which came back negative.. On an unknown date, Gastrointestinal pathogen panel: Gastrointestinal Pathogen Panel PCR Feces also came back negative.. On an unknown date, Lumbar puncture: was performed which showed elevated protein, WBC, and glucose.. On an unknown date, Magnetic resonance imaging head: was unremarkable pre and postcontrast without focal findings or abnormal enhancement and showed redemonstration of the C1-C2 subluxation as described on CT scan.. On an unknown date, Magnetic resonance imaging spinal: MRI of cervical spine showed at the level of C1 there is spinal canal stenosis. However, there is no direct pressure upon the cord/medulla..     For mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown), the reporter considered GUILLAIN-BARRE SYNDROME (Guillain-Barre Syndrome) to be related. No further causality assessment was provided for DIARRHOEA (diarrhea/abdominal pain/fevers/fatigue).    Concomitant medications were not reported.  Patient presented to the ED complaining of generalized weakness and acute loss of ability to ambulate which has been progressing for a month. Patient began having left arm and leg weakness, which started in his fingertips of his left upper extremity and soon moved proximally to upper left arm. Symptoms then progressed to right upper and lower arms. Symptoms further continued to progress making the patient bedridden.  Upon evaluation, patient had significant motor weakness and required maximal assistance for movement. Patient was moreover noted to have flaccidity of muscles associated with weakness with no bulbar weakness. Patient had no difficulty in breathing or with speech.  Upon further investigation, patient stated that patient received (3rd dose) of the Moderna Vaccine for COVID-19 about a month before the onset of symptoms and felt fine. Two weeks later, patient began experiencing subjective fevers, diarrhea, abdominal pain, and fatigue that lasted for a week and then self-resolved. Approximately another two weeks later is when patient began noticing his neurological symptoms.  Possible Guillain-Barre Syndrome post Campylobacter infection vs. post Covid-19 vaccine induced GBS was suspected at this point. Patient was discharged to a rehab center and planned to receive another round of IVIG for 5 days.  Author concluded that there had also been several case reports and studies that had shown increased incidence of GBS vaccines such as influenza vaccine. Furthermore, there had been several studies that had linked GBS to COVID-19 vaccine. With COVID-19 cases continuing to persist, and increasing advocacy for vaccination against the disease, GBS should be considered as very rare but possible side effect of the vaccine.  Company comment: This is a literature non-study case concerning a 50- year-old, male patient with no reported medical history, who experienced the serious (due to medically significant  and hospitalization) unexpected, AESI of Guillain Barre Syndrome. The event occurred approximately 1 month after the third dose of mRNA-1273 vaccine. Patient presented to the ED complaining of generalized weakness and acute loss of ability to ambulate which has been progressing for a month. Patient began having left arm and leg weakness, which started in his fingertips of his left upper extremity and soon moved proximally to upper left arm. Symptoms then progressed to right upper and lower arms. Symptoms further continued to progress making the patient bedridden. Diagnostic test performed shown CT head and spine: showed C1-C2 subluxation, possibly chronic. Magnetic resonance imaging head was unremarkable. Negative culture stool for, and gastrointestinal pathogen panel PCR feces. Lumbar puncture: was performed which showed elevated protein, white blood cells and glucose. Possible Guillen Barre was suspected, and the patient started with Ig IV.The outcome of the event was reported as not recovered. Two weeks after vaccination the patient also experienced the non-serious events of diarrhea, fever and fatigue which solved. The benefit-risk relationship of mRNA-1273 vaccine is not affected by this report.   Most recent FOLLOW-UP information incorporated above includes: On 24-May-2023: Live follow up received by safety on 25-May-2023 has email with full text article and contains no new information.; Sender's Comments: This is a literature non-study case concerning a 50- year-old, male patient with no reported medical history, who experienced the serious (due to medically significant  and hospitalization) unexpected, AESI of Guillain Barre Syndrome. The event occurred approximately 1 month after the third dose of mRNA-1273 vaccine. Patient presented to the ED complaining of generalized weakness and acute loss of ability to ambulate which has been progressing for a month. Patient began having left arm and leg weakness, which started in his fingertips of his left upper extremity and soon moved proximally to upper left arm. Symptoms then progressed to right upper and lower arms. Symptoms further continued to progress making the patient bedridden. Diagnostic test performed shown CT head and spine: showed C1-C2 subluxation, possibly chronic. Magnetic resonance imaging head was unremarkable. Negative culture stool for C. Jejuni, and gastrointestinal pathogen panel PCR feces. Lumbar puncture: was performed which showed elevated protein, white blood cells and glucose. Possible Guillen Barre was suspected, and the patient started with Ig IV.The outcome of the event was reported as not recovered. Two weeks after vaccination the patient also experienced the non-serious events of diarrhea, fever and fatigue which solved. The benefit-risk relationship of mRNA-1273 vaccine is not affected by this report.