Aseptic Meningitis, Mucocutaneous Lesions and Arthritis after COVID-19 Vaccination in a 15-Year-Old Boy.

We report a 15-year-old boy who developed aseptic meningitis 10 days after administration of the second dose of the COVID-19 vaccine BNT162b2. Although accompanying aphthous mouth ulcers resembling herpetic stomatitis initially led us to suspect an underlying viral infection, broad virological and microbiological screening did not identify any causative pathogen. Gonarthritis and skin lesions, which both developed within three days after admission, extended the clinical presentation eventually resembling an acute Behçet's disease episode. This is the first description of a juvenile patient with aseptic and pathogen-negative meningitis occurring in close temporal association with vaccination against COVID-19, along with a few previously reported adult patients with isolated meningitis and a further case with meningitis and an accompanying Behçet's disease-like multisystem inflammation episode as seen in our patient. With billions of individuals being vaccinated worldwide so far and only a few cases of aseptic pathogen-negative meningitis reported in close temporal relation, causality is unclear. However, aseptic meningitis should be kept in mind in the differential diagnosis of patients with persistent or delayed onset of headache and fever following COVID-19 vaccination.