Before the vaccine, the U.S. experienced approximately 3 to 4 million cases a year with approximately 500 annual deaths. In the 80’s, several outbreaks occurred in college campuses and sports arenas – thus changing the requirements for college entry to include vaccination. The 1991 measles outbreak in Philadelphia claimed 9 lives amongst the 1400 cases – the ratio of case fatalities was 1.2% even with modern medicine/supportive care available.
