Measles
The spring of my first year at Binghamton University (back in the 80’s) I looked forward to many things: getting all the stupid electives behind me so I could strictly focus on math and music the next three years, and the Spring Fling festival coming up the following week. In particular, the Monks of Doom were going to perform at said festival - I had just discovered them and therefore I was stoked.
Word started to spread around campus that a student attending another university in upstate New York came down with the measles of all things. And then a second student at another nearby college fell ill with the same.
The response was swift. All universities in the region were completely quarantined. With less than 24 hour notice every student, faculty, and staff member (i.e. over 10,0000 people) were instructed to make their way to the stadium to get MMR shots. I remember long lines that moved quickly. I was eventually ushered into the queue for all students whose last names start with "L." At the front line they had dot matrix printouts of all pertinent names. I was checked off, jabbed with a needle, and presented with a certificate to prove I got vaccinated (necessary for attending class and other functions for the next while). And that was that!
On hindsight this well organized and executed response was quite impressive, especially given the pre-world-wide-web level of internet and database technology at the time (1989). The outbreak was neutralized almost immediately. However, given the quarantine, they cancelled Spring Fling which was a massive bummer. But less than four years later I ended up moving to the Bay Area and saw Monks of Doom open up for King Missile at the Berkeley Square. Great show.