a health crisis at an ivy league school, princeton university. an outbreak of an unusual potentially deadly strain of meningitis. and it is so serious, that the cdc is taking an unprecedented step tonight. they are rushing to get a vaccine, that might help control the outbreak, even though that vaccine is not yet approved here in the united states. abc's linsey davis has the details. >> reporter: with seven cases of meningitis diagnosed at princeton since march, new jersey health officials declared an outbreak. >> it is very serious. >> reporter: so serious in fact the cdc is taking the unprecedented move of importing emergency doses of the meningitis vaccine not yet approved for use in this country. late today government health officials confirmed, they have agreed to import bexsero. it is currently licensed in europe and australia. it protects against meningitis b, the particular strain the students have been diagnosed with. bacterial meningitis is a dangerous infection of...