Developing a vaccine for meningitis B was tricky. Even the existing vaccine doesn't protect against all B strains. Josef Muellek/iStockphoto.com hide caption

itoggle caption Josef Muellek/iStockphoto.com

The Ivy League school has begun vaccinating nearly 6,000 students to try to stop an outbreak of type B meningitis in an unusual federal government-endorsed administration of a drug not generally approved for use in the U.S. Mel Evans/AP hide caption

itoggle caption Mel Evans/AP

Administrators at University of California, Santa Barbara are encouraging fraternities and sororities to hold off on parties. Damian Gadal/Flickr hide caption

itoggle caption Damian Gadal/Flickr

Six students and a visitor have fallen ill with meningitis at Princeton University in New Jersey, shown here in August 2013. All have recovered or are recovering, officials said. Bloomberg via Getty Images hide caption

itoggle caption Bloomberg via Getty Images

Princeton University's Nassau Hall. DANIEL HULSHIZER/AP hide caption

itoggle caption DANIEL HULSHIZER/AP