Dear Rob, I read it in Infectious Diseases in Children.  I read it in the
past year, but I'm not sure if I saved the article.  We've been giving all
babies over 6 mo monovalent measles and then MMR at 15 mo.(especially if
they are going overseas as many of our babies do.   Red book says 95% vac
at 12 mo are immune, 98% vac at 15 mo are immune.  "However, a very small
percentage of vaccinated individuals may lose protection after several
years.  More than 99% of persons who receive two doses separated by at
least 1 mo (4 weeks) and on or after their first birthday develop serologic
evidence of measles immunity." p. 348
Sincerely, Pat in SNJ