Meningococcal vaccine
The meningococcal vaccine protects against diseases caused by the bacterium Neisseria meningitidis, a leading cause of bacterial meningitis, particularly in crowded environments such as dormitories and military barracks. Symptoms of meningococcal meningitis can include headache, stiff neck, and fever, escalating rapidly to severe complications like bloodstream infection and shock. In the United States, two primary types of meningococcal vaccines are available: the meningococcal conjugate vaccines (MenACWY), which target serotypes A, C, W, and Y, and the Meningococcal serogroup B vaccines (MenB), which specifically protect against serotype B.
The vaccine works by linking the bacterium's polysaccharide coating to a protein, prompting the immune system to produce a protective response without causing the disease. The vaccine's development has evolved since the late 1960s, with improvements to include multiple serotypes, leading to the licensing of newer conjugate vaccines in 2005 and 2015. It is recommended for all children at ages eleven to twelve, with a booster at sixteen, and is also advised for those in high-risk situations. The introduction of this vaccine has significantly decreased the rates of meningitis and its severe consequences, though other bacterial causes of meningitis remain.
Meningococcal vaccine
- ALSO KNOWN AS: Neisseria meningitidis vaccine
Definition
The meningococcal vaccine protects against disease caused by Neisseria meningitidis. This bacterium is a very serious cause of bacterial meningitis. It is most virulent in areas where many people live together in close contact, such as dormitories or military barracks. Meningococcal meningitis can present with headache, stiff neck, and fever, progressing rapidly to bloodstream infection (meningococcemia), shock, and death. There are two types of meningococcal vaccines available in the United States. Meningococcal conjugate vaccines (MenACWY) protect against serotypes A, C, W, and Y of Neisseria meningitidis, and Meningococcal serogroup B vaccines (MenB) protect against serotype B.
Mechanism of Action
The vaccine is made by linking the shell, or polysaccharide coating, of the N. meningitidis bacterium to another protein. Injection of this safe combination incites the body to produce an immune response against this bacterial coating without causing the disease, thus protecting against future infection.
Complicating matters, however, is that there are twelve different types of this bacterium. To be an effective vaccine, each polysaccharide coating from each bacterium must be isolated and incorporated into the vaccine. Not all types have been isolated and included in the vaccine.
Vaccine History
The first meningococcal vaccines were polysaccharide vaccines developed in the late 1960s and 1970s that protected against only one type of N. meningitidis. The vaccine was further improved by adding protection against more types of meningococcal bacteria. In the 1980s, quadrivalent polysaccharide vaccines were developed targeting multiple serotypes. Meningococcal conjugate vaccines were licensed in 2005 and included protection against four known types: A, C, Y, and W-135. Serogroup B vaccines were licensed in 2104 and 2015 and targeted serotype B specifically.
Vaccine Administration
Medical experts recommend that the meningococcal vaccine be given to all children once they reach eleven or twelve years of age. It is usually administered to the family doctor or other health care provider at the standard preadolescent visit. A booster dose is necessary once the patient turns sixteen. First-year students moving into dormitories, individuals joining the military, people with compromised immune systems, and travelers to certain areas may also be administered the vaccine.
Impact
N. meningitidis is a particularly dangerous cause of bacterial meningitis, with an estimated mortality rate of between 10 and 15 percent despite prompt and appropriate antibiotic treatment. Likewise, fulminant meningococcemia carries an estimated mortality rate of between 30 and 50 percent in spite of antibiotics. Without treatment, both of these diseases are fatal. Even with treatment, long-term survivors often grapple with chronic health conditions caused by infection. The meningococcal vaccine has dramatically reduced the morbidity and mortality attributed to these diseases. It is important to note that other bacterial causes of meningitis still exist. Still, the incidence of meningitis overall has dramatically declined since the meningococcal vaccine was added to the routine immunization schedule.
Bibliography
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