The vast majority of people who come into contact with the bacteria do not become ill but occasionally the bacteria can invade the body and cause serious illness.
They can be given to babies and young adults.
Little girl, 6, dies from meningitis after tell-tale rash was #8216;mistaken for bruises#8217;
As a result the Men W jab was added to the national immunisation programme in August 2015.
Meningitis Research Foundation