Posterior Reversible Encephalopathy Syndrome; This literature-non-study case was reported in a literature article and describes the occurrence of POSTERIOR REVERSIBLE ENCEPHALOPATHY SYNDROME (Posterior Reversible Encephalopathy Syndrome) in a 76-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 prophylaxis.   LITERATURE REFERENCE:  Concurrent medical conditions included Hypertension (managed with a beta-blocker).    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,  after starting mRNA-1273 (Moderna COVID-19 Vaccine), the patient experienced POSTERIOR REVERSIBLE ENCEPHALOPATHY SYNDROME (Posterior Reversible Encephalopathy Syndrome) (seriousness criterion medically significant). At the time of the report, POSTERIOR REVERSIBLE ENCEPHALOPATHY SYNDROME (Posterior Reversible Encephalopathy Syndrome) outcome was unknown.        For mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown), the reporter considered POSTERIOR REVERSIBLE ENCEPHALOPATHY SYNDROME (Posterior Reversible Encephalopathy Syndrome) to be related.    Concomitant and treatment medications were not reported.  Patient presented with the acute onset of neurological changes. Her clinicoradiological findings were most consistent with posterior reversible encephalopathy syndrome (PRES).  Reporter stated that although PRES has been reported with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, this raised suspicion of a possible vaccine-induced PRES with her only confounder being hypertension managed with a beta-blocker. Extensive workup for other entities associated with PRES, including infection, autoimmune, paraneoplastic syndrome, and alcohol were unrevealing.   Company comment: This is a literature-non-study case concerning  a  76-year-old, female patient with no relevant medical history, who experienced the unexpected serious (medically significant) event of Posterior reversible encephalopathy syndrome. The events occurred on an unknown day after the third dose of mRNA-1273 COVID 19 Vaccine.The event outcome was unknown. The reporter assessed the events as related to the product. No further details on clinical course, lab test results and treatment received were reported. The concurrent medical conditions of Hypertension (managed with a beta-blocker) remains a confounder. The benefit-risk relationship of mRNA-1273 COVID 19 Vaccine, is not affected by this report. Event seriousness is assessed as per regulatory authority's report.; Sender's Comments: This is a literature-non-study case concerning  a  76-year-old, female patient with no relevant medical history, who experienced the unexpected serious (medically significant) event of Posterior reversible encephalopathy syndrome. The events occurred on an unknown day after the third dose of mRNA-1273 COVID 19 Vaccine.The event outcome was unknown. The reporter assessed the events as related to the product. No further details on clinical course, lab test results and treatment received were reported. The concurrent medical conditions of Hypertension (managed with a beta-blocker) remains a confounder. The benefit-risk relationship of mRNA-1273 COVID 19 Vaccine, is not affected by this report. Event seriousness is assessed as per regulatory authority's report.