For what it’s worth, it seems like even the smart people don’t seem concerned about needing a booster if you had the normal two doses as a kid.
The information that I'm going on is that if you were born in the USA in:
-1957 -- It is assumed you probably got measles as a kid and therefore possess immunity.
1958-1967 -- You
might have been vaccinated once, but you also
might have gotten the discontinued vaccine that does NOT confer long-term immunity, so you
might want to get two new doses.
1968-1988 -- You were probably vaccinated at least once with the "good" vaccine, but you might want to check and see if you need to update that with a second dose.
1989- -- You were probably vaccinated twice with the "good" vaccine and should be fine, but you might want to check your records just to make sure.
--Patrick