Metabotropic glutamate receptor 5 (mGluR5)-related autoimmune encephalitis (AE) has been rarely reported; however, there are no reports on mGluR5-related AE with reversible splenial lesion syndrome following vaccination against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The gene discussed is GRM5; the disease is autoimmune encephalitis.