Posterior Reversible Encephalopathy Syndrome Onset Within 24 Hours Following Moderna mRNA Booster COVID-19 Vaccination: Vaccine Adverse Event Vs. Hypertension?

We present a case of a female who presented with the acute onset of neurological changes within 24 hours of receiving her third, or booster, dose of the mRNA Moderna (Cambridge, Massachusetts) coronavirus disease 2019 (COVID-19) vaccination. Her clinicoradiological findings were most consistent with posterior reversible encephalopathy syndrome (PRES). 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. Thus far, there have not been any reports of PRES post mRNA vaccination. We encourage providers to report similar cases with neurological manifestations post mRNA vaccination to the vaccine adverse event reporting system (VAERS). Timely diagnosis and treatment of PRES may help minimize any irreversible neurological sequelae.