Meningococci are a type of bacteria known scientifically as Neisseria meningitidis. They can cause serious infections, particularly meningitis, which is an inflammation of the protective membranes covering the brain and spinal cord. Meningococci are spread through respiratory droplets, making close contact with an infected person a common way to contract the bacteria. There are several strains of meningococci, with serogroups A, B, C, W, and Y being the most significant in terms of disease. Vaccines are available to protect against some of these strains, and vaccination is especially recommended for adolescents and people in crowded settings, such as college dormitories.