When does subacute sclerosing panencephalitis develop?

Subacute sclerosing panencephalitis (SSPE) typically develops in children and adolescents who have previously been infected with measles or received the measles, mumps, and rubella (MMR) vaccine. The average time between the initial measles infection or MMR vaccination and the onset of SSPE symptoms is 7 to 10 years, but it can range from a few months to several decades.