Meningitis is a term used to refer to inflammation of the meninges, the tissue covering the brain.
This is often caused by infection. One type of microbe that causes meningitis is Neisseria meningitidis and this leads to a disease called Invasive Meningeal Disease (IMD). IMD is an aggressive form of infection that quickly spreads to the blood and nervous system causing high fever, severe headache, a rash and can deteriorate to loss of arms or legs, coma and death.
Neisseria meningitidis is a very common microbe, mostly residing in the throat of carriers without
causing any harm. It is estimated that around 10% of people have it. Transmission is by droplets of
saliva as when breathing into another person's face, sharing of eating utensils, sneezing without
covering the face and poor hand hygiene.
Problems arise when Neisseria starts to multiply uncontrollably such as in people with weakened
immune systems. There are 5 subtypes of this meningitis microbe, namely ABCWY. Up till recently
there was a vaccine available for subtypes ACW and Y. Subtype B was not covered. This situation
changed when a shot targeted at the B subtype became commercially available and the demand for
it was (and still is) huge. This in part was aided by news stories of deaths in children having been
stricken by meningitis B and the consequent emotional outpour duly amplified on social media
platforms such as Facebook and Twitter. In Malta you had people going over to Sicily with cooler
bags to buy the vaccine and bring it over.
A close look at the facts reveals that IMD is a rare disease with two major peaks of incidence. The
first occurs in the first year of life and the second peak towards teenage. The first peak is much more
significant than the second. Furthermore the currently available vaccine covers against around 80%
of type B Neisseria meningitidis and the duration of immunity beyond 48 months is unknown. This
means that widespread use of this vaccine will presumably cause natural selection for the uncovered
20% of strains, thus rendering the vaccine useless in the long term.
Two respected internationally recognised organisations have issued different recommendations with
regards immunisation with meningitis B vaccine in healthy individuals. These are the British NHS and
the Center for Disease Control (CDC) of the United States. The NHS recommends that the meningitis B vaccine is given to all children in the first year of life together with the other routine vaccines. This approach assures protection during the age wheninfection with the meningitis B bacterium is most likely. However there is no assurance that the child will remain covered through life. CDC on the other hand recommends giving the vaccine to children as they reach teenage.
One should note that the vaccine is considered safe to all effects but it does carry the risk of side
effects such as pain at injection site, fever, loss of appetite and nausea.
So in conclusion I have to say that the development of this vaccine has been a welcome
development, but more research is needed to increase the range of protective cover it provides and
to elucidate the length of immunity it affords.
