CD40LG and aseptic meningitis: We found 1 case of aseptic meningitis in a breast-feeding infant, which is very rare (only 3 cases with IgM in the CSF of breast-feeding infants have been reported to date [19–21]), and 3 cases of immune-mediated encephalitides (3 neuronal surface antibody encephalitides and 1 case of antibody-negative opsoclonus-myoclonus-ataxia), which are not traditionally associated with the YF vaccine.