Two students from a university dormitory building have contracted meningitis due to Neisseria meningitides. Which of the following students in the dormitory are most likely to benefit from chemoprophylaxis?

Although only close contacts need chemo-prophylaxis, it is sometimes given more widely than recommended because of community concern. Meningococcal vaccine is effective against serotype A and C, and will prevent late secondary infection in close contacts. Ciprofloxacin or ofloxacin are alternatives to rifampin.