guillain barre syndrome; this case was received via ra (reference number: gb-mhra-adr 26636234) on 23-feb-2022 and was forwarded to moderna on 23-feb-2022. this regulatory authority case was reported by a physician and describes the occurrence of guillain-barre syndrome (guillain barre syndrome) in a female patient of an unknown age who received mrna-1273 (moderna covid-19 vaccine) for an unknown indication. no medical history information was reported. on 02-jan-2022, the patient received third dose of mrna-1273 (moderna covid-19 vaccine) (unknown route) 1 dosage form. on 30-jan-2022, the patient experienced guillain-barre syndrome (guillain barre syndrome) (seriousness criterion hospitalization). at the time of the report, guillain-barre syndrome (guillain barre syndrome) was resolving. the action taken with mrna-1273 (moderna covid-19 vaccine) (unknown) was unknown. for mrna-1273 (moderna covid-19 vaccine) (unknown), the reporter did not provide any causality assessments. concomitant medications were not provided. the dosage text for suspect covid-19 vaccine moderna was reported as dose 3b. treatment medications were not provided. the report was not related to possible blood clots or low platelet counts the report was not related to possible myocarditis or pericarditis. relevant investigations or tests conducted were lp, nerve conduction studies. patient had not tested positive for covid-19 since having the vaccine and was unsure if patient was enrolled in clinical trial. it was unsure if patient had symptoms associated with covid-19, not had a covid-19 test. company comment: this is a regulatory case concerning a female patient of an unknown age with no reported medical history, who experienced the serious (hospitalization) unexpected aesi guillain barre syndrome, approximately 28 days after the third dose of mrna-1273. clinical course and treatment details were not provided. nerve conduction studies was performed: results was not reported. the benefit-risk relationship of mrna-1273 is not affected by this report.; sender's comments: company comment: this is a regulatory case concerning a female patient of an unknown age with no reported medical history, who experienced the serious (hospitalization) unexpected aesi guillain barre syndrome, approximately 28 days after the third dose of mrna-1273. clinical course and treatment details were not provided. nerve conduction studies was performed: results was not reported. the benefit-risk relationship of mrna-1273 is not affected by this report