His doctor said he had symptoms of Guillain-Barre Syndrome; Patient couldn't walk good a week after 1st dose; Father stated that patient couldn't walk good, he had been crying, is still crying; Hurting near groin area; Patient is also hardly eating now; Hurting near hip area; This spontaneous case was reported by a consumer (subsequently medically confirmed) and describes the occurrence of GUILLAIN-BARRE SYNDROME (His doctor said he had symptoms of Guillain-Barre Syndrome) and GAIT DISTURBANCE (Patient couldn't walk good a week after 1st dose) in a 22-year-old male patient who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.     Concurrent medical conditions included Autistic disorder (Non verbal Autistic.).    On 03-Aug-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) 1 dosage form. In August 2021, the patient experienced GUILLAIN-BARRE SYNDROME (His doctor said he had symptoms of Guillain-Barre Syndrome) (seriousness criteria disability and medically significant), GAIT DISTURBANCE (Patient couldn't walk good a week after 1st dose) (seriousness criterion disability), CRYING (Father stated that patient couldn't walk good, he had been crying, is still crying), GROIN PAIN (Hurting near groin area), FEEDING DISORDER (Patient is also hardly eating now) and ARTHRALGIA (Hurting near hip area). At the time of the report, GUILLAIN-BARRE SYNDROME (His doctor said he had symptoms of Guillain-Barre Syndrome), GAIT DISTURBANCE (Patient couldn't walk good a week after 1st dose), CRYING (Father stated that patient couldn't walk good, he had been crying, is still crying), GROIN PAIN (Hurting near groin area), FEEDING DISORDER (Patient is also hardly eating now) and ARTHRALGIA (Hurting near hip area) had not resolved.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): In August 2021, Ultrasound scan: normal (normal) ultrasound was done on both his legs. Everything appeared to be normal.     mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) dosing remained unchanged.       No concomitant and treatment medication information were provided.   On an unknown date in Aug-2021 (about a week after), the patient couldn't walk good, had been crying and hurting near his groin area. Thought patient might have a gout issue. Patient was also hardly eating. The patient did an ultrasound on both his legs everything appeared to be normal.  The doctor said the patient had symptoms of Guillain-Barre Syndrome and suggested that should call Moderna.   Father reported on follow-up, that he was taking his son to the ER. Reported he had partial paralysis and non-verbal. Reporter stated his son was progressively getting worse every day since receiving the Moderna COVID-19 vaccine and said. Caller mentioned that they would going to tell the doctors they think it was caused by the shot.  Company Comment : This case concerns a 22 year old male with history of  non-verbal autistic disorder who experienced serious unexpected event of GBS after the first dose of the vaccine. Medical history of non-verbal autistic disorder is a confounder. Rechallenge was not applicable. The benefit-risk relationship is not affected by this report.   This case was linked to MOD-2021-336161.   Most recent FOLLOW-UP information incorporated above includes: On 30-Sep-2021: Upon follow-up receipt: inarrative updated.; Sender's Comments: This case concerns a 22 year old male with history of  non-verbal autistic disorder who experienced serious unexpected event of GBS after the first dose of the vaccine. Medical history of non-verbal autistic disorder is a confounder. Rechallenge was not applicable. The benefit-risk relationship is not affected by this report.