There’s still time for the other 2.
It has been estimated that about 2 in 10,000 people who get measles will eventually develop SSPE. However, a 2016 study estimated that the rate for unvaccinated infants under 15 months was as high as 1 in 609. No cure for SSPE exists, and the condition is almost always fatal.
SSPE is characterized by a history of primary measles infection, followed by a normal, unremarkable recovery. Symptoms of SSPE appear later. On average, the first symptoms appear about 10 years after the initial infection