Between 1956 and 1960, there were an average of 450 children killed by measles every year. There were approximately 1500 additional cases of measles encephalitis per year, often with permanent brain damage. Between 1951 and 1954, there were an average of 1870 children killed per year by polio.
Why are you using 60 year old medical figures for today?
encephalitis is listed on the CDC website, and on the package insert as possible side but rare side effects.
I posted upthread the only places where there are polio outbreaks now are they use the oral vaccination. We don’t use it here, but we don’t mind shipping it elsewhere.