About 1 in 20 children with meningitis caused by meningococcus and about 1 in 3 children with bloodstream infections (i.e., sepsis) caused by meningococcus will die from the infection. Death from sepsis can occur within 12 hours of the beginning of the illness. Meningococcus is one of the most rapid and overwhelming infectious diseases known to man.
What is meningococcus?
The bacterium, Neisseria meningitidis, primarily targets children younger than 1 year of age. Because meningococcus is contagious, outbreaks can occur in childcare centers and schools. Cases also occur in high schools and on college campuses.
Meningococcus usually causes meningitis (inflammation of the lining of the brain) or sepsis (an infection of the bloodstream). Symptoms of meningitis include stiff neck, headache, fever and drowsiness. Symptoms of sepsis caused by meningococcus include fever, shock and coma. The disease is so rapid that a child can be perfectly well and, in a matter of only a few hours, be in a coma. For these reasons, meningococcal infections that occur in childcare centers, elementary schools or high schools often cause panic in the community. Every year about 800 to 1,500 people in the United States are infected with meningococcus and about 120 die. Meningococcus can also cause pneumonia and arthritis.
Consequences of meningococcal infection occur in about 12 of every 100 survivors and include limb amputation, skin grafting, hearing loss, seizures, kidney disease and mental retardation. About 10 of every 100 people infected with meningococcus will die from the disease. Immunization is the most effective way to reduce the incidence of death and permanent sequelae caused by meningococcus.
How do you catch meningococcal infection?
Usually meningococcal infection is acquired after intimate contact with an infected person. Intimate contact includes kissing, sharing food or beverages, or staying in the same house or room (including a classroom) for more than four hours a day.
Because smoking disrupts the lining of the throat, people who smoke are at increased risk of some infections, including pneumococcus and meningococcus. Both of these vaccine-preventable diseases can cause meningitis.
How are the meningococcal vaccines made?
Two types of meningococcal vaccines are available. One has been available for several years and protects against four of the five types of meningococcus (A, C, Y, and W-135). The other version is newer and protects against the fifth type of meningococcus, type B.
Meningococcus A, C, Y and W-135 vaccine
This meningococcal vaccine is similar to those for pneumococcus and Haemophilus influenzae type b (Hib) in that protection against disease occurs when one develops antibodies to the sugar (or polysaccharide) that coats the bacterium. A meningococcal vaccine, made using only the polysaccharide coating of meningococcus, has been available for several years. Unfortunately, children less than 2 years of age are not very good at making immune responses to the polysaccharide alone.
In order for young children to make an immune response, the polysaccharide must first be attached to a harmless protein. (see How Are Vaccines Made?). The polysaccharide attached to the protein is known as a conjugate vaccine. There are two conjugated meningococcal vaccines:
- One, available since 2005, can be given to people between 9 months and 55 years of age
- The second, available since February 2010, can be used in people between 2 and 55 years of age
In both vaccines, the polysaccharides have been stripped from the surface of four of the five different types of meningococcal bacteria that cause disease and each is linked to a harmless protein. The four conjugated polysaccharides are combined into a single shot.
Meningococcal B vaccine
Hib and pneumococcal vaccines have been easier to make than the meningococcal vaccine. The Hib vaccine was easier to make because there is only one type of Haemophilus influenzae that commonly causes severe disease in children (type b). The pneumococcal vaccine was easier to make than the meningococcal vaccine because, although there are about 90 different types of pneumococcus, most of the disease in children is caused by 13 types. Therefore, the pneumococcal vaccine contains these 13 different types of polysaccharides — each linked to a protein.
Although there are only five different types of meningococcus that commonly cause disease (types A, B, C, Y and W-135), it has been very difficult to make a vaccine that includes type B, and meningococcus type B accounts for two-thirds of meningococcal infections in infants and one-third of meningococcal infections in adolescents and adults. Two vaccines to prevent meningococcus type B were licensed for use in adolescents in 2015 — Bexsero® and Trumenba®. Both of these vaccines were made using proteins, not polysaccharides, that reside on the surface of the bacteria. Trumenba contains two proteins, and Bexsero contains four.
Who should get the meningococcal vaccine?
The A, C, Y, W-135 meningococcal vaccine is recommended for:
- Adolescents and teens 11 to 18 years old
- Children and adults without a spleen (see additional information about MenHibRix® below)
- Children and adults who lack a particular group of serum proteins, called complement proteins, that help the body fight infection (see additional information about MenHibRix® below)
- College freshmen living in dormitories
- People exposed to someone infected with meningococcus during an outbreak if the type of meningococcus is one contained in the vaccine (types A, C, Y or W-135)
- Children and adults who will be traveling to sub-Saharan Africa between December and June
- Military recruits
- Lab workers who work with the bacteria
The meningococcal B vaccine is recommended for:
- All 16- to 18-year olds
- People aged 10 years and older who have complement deficiencies, no spleen or a spleen that does not function
- Lab workers who work with the bacteria
- People exposed to someone infected with meningococcus type B during an outbreak, such as on a college campus
Does the meningococcal vaccine have side effects?
The meningococcal vaccines may cause pain or tenderness where the shot is given, but do not cause any serious side effects. Although a possible association with Guillian-Barre Syndrome (GBS) was investigated, no causal association was found.