New-Onset Myasthenia Gravis Confirmed by Electrodiagnostic Studies After a Third Dose of SARS-CoV-2 mRNA-1273 Vaccine.

Coronavirus disease 2019 vaccine-related pathology is a rare occurrence with few reported cases. We report on a case of a 60-yr-old man experiencing symptoms of dysphagia, dysarthria, diplopia, and weakness with onset 6 days after receiving a third full dose of SARS-CoV-2 vaccine (mRNA-1273 vaccine) in August 2021, which he received outside of the Center for Disease Control recommended guidelines, at 4 mos after his second dose of the Moderna vaccination course in March 2021. The Food and Drug Administration Emergency Use Authorization for mRNA-1273 booster was established in October 2021.