|The examples and perspective in this article may not represent a worldwide view of the subject. (September 2012)|
Neisseria meningitidis has 13 clinically significant serogroups, classified according to the antigenic structure of their polysaccharide capsule. Six serogroups, A, B, C, Y, W135 and X are responsible for virtually all cases of the disease in humans.
Quadrivalent (Serogroups A, C, W-135 and Y)
There are currently three vaccines available in the US to prevent meningococcal disease, all quadrivalent in nature, targeting serogroups A, C, W-135 and Y:
- two conjugate vaccines (MCV-4), Menactra and Menveo, and
- one polysaccharide vaccine (MPSV-4), Menomune, produced by Sanofi Pasteur.
Nimenrix (GlaxoSmithKline), a new quadrivalent conjugate vaccine against serogroups A, C, W-135 and Y is currently available in the states of the European Union and some additional countries.
The first meningococcal conjugate vaccine (MCV4), Menactra, was licensed in the U.S. in 2005 by Sanofi Pasteur; Menveo, was licensed in 2010 by Novartis. Both MCV4 vaccines have been approved by the Food and Drug Administration (FDA) for people 2 through 55 years of age. Menactra received FDA approval for use in children as young as 9 months in April 2011 while Menveo received FDA approval for use in children as young as 2 months in August 2013. The Centers for Disease Control and Prevention (CDC) has not made recommendations for or against its use in children less than 2 years.
Meningococcal polysaccharide vaccine (MPSV4), Menomune, has been available since the 1970s. It may be used if MCV4 is not available, and is the only meningococcal vaccine licensed for people older than 55. Information about who should receive the meningococcal vaccine is available from the CDC.
The duration of immunity mediated by Menomune (MPSV4) is three years or less in children aged under 5 because it does not generate memory T cells. Attempting to overcome this problem by repeated immunization results in a diminished not increased antibody response, so boosters are not recommended with this vaccine. As with all polysaccharide vaccines, Menomune does not produce mucosal immunity, so people can still become colonised with virulent strains of meningococcus, and no herd immunity can develop. For this reason, Menomune is suitable for travelers requiring short-term protection, but not for national public health prevention programs.
Menveo and Menactra contain the same antigens as Menomune, but the antigens are conjugated to a diphtheria-toxoid polysaccharide–protein complex, resulting in anticipated enhanced duration of protection, increased immunity with booster vaccinations, and effective herd immunity.
A study published in March 2006 comparing the two kinds of vaccines found that 76% of subjects still had passive protection three years after receiving MCV-4 (63% protective compared with controls), but only 49% has passive protection after receiving MSPV-4 (31% protective compared with controls). As of 2010, there remains limited evidence that any of the current conjugate vaccines offer continued protection beyond three years; studies are ongoing to determine the actual duration of immunity, and the subsequent requirement of booster vaccinations. The CDC offers recommendations regarding who they feel should get booster vaccinations.
Bivalent (Serogroups C and Y)
On June 14, 2012, the FDA approved a new combination vaccine against two types of meningococcal diseases and Hib disease for infants and children 6 weeks to 18 months old. The vaccine, Menhibrix, will prevent disease caused by Neisseria meningitidis serogroups C and Y, and Haemophilus influenzae type b. This is the first meningococcal vaccine that can be given to infants as young as six weeks old.
A vaccine called MenAfriVac has been developed through a program called the Meningitis Vaccine Project and has a potential of preventing outbreaks of group A meningitis which is common in sub-Saharan Africa.
Vaccines against serotype B meningococcal disease have proved difficult to produce, and require a different approach from vaccines against other serotypes. Whereas effective polysaccharide vaccines have been produced against types A, C, W, and Y, the capsular polysaccharide on the type B bacterium is too similar to human neural antigens to be a useful target.
A vaccine for serogroup B was developed in Cuba in response to a large outbreak of meningitis B during the 1980s. The VA-MENGOC-BC vaccine proved safe and effective in randomized double-blind studies, but it was granted a license only for research purposes in the United States as political differences limited cooperation between the two countries.
Due to a similarly high prevalence of B-serotype meningitis in Norway between 1975 and 1985, Norwegian health authorities developed a vaccine specifically designed for Norwegian children and young adolescents. Clinical trials were discontinued after the vaccine was shown to cover only slightly more than 50% of all cases. Furthermore, lawsuits for damages were filed against the State of Norway by persons affected by serious adverse reactions. Information that the health authorities obtained during the vaccine development were subsequently passed on to Chiron (now a Novartis subsidiary), who developed a similar vaccine, MeNZB, for New Zealand.
A new MenB vaccine was approved for use in Europe in January 2013. Following a positive recommendation from the European Union's Committee for Medicinal Products for Human Use, Bexsero®, produced by Novartis, received a license from the European Commission. However, deployment in individual EU member states still depends on decisions by national governments. In July 2013, the United Kingdom's Joint Committee on Vaccination and Immunisation (JCVI) issued an interim position statement recommending against adoption of Bexsero as part of a routine meningococcal B immunisation program.
In November 2013, in response to an outbreak of B-serotype meningitis on the campus of Princeton University, the acting head of the Centers for Disease Control meningitis and vaccine preventable diseases branch told NBC News that they had authorized emergency importation of Bexsero to stop the outbreak.
The occurrence of serogroup X was reported in North America, Europe, Australia, and West Africa. Current meningoccocal meningitis vaccine is not known to protect from serogroup X N. meningitidis disease.
- Medical Subject Headings (MeSH)