The Turnstone: talking about vaccines #30

Is meningitis still a threat? (5 minute read)

I can remember many years ago, when I was a student, meningitis was one of New Zealand’s most feared diseases. Most frightening was its speed – someone, usually a child or teenager, could go from apparently healthy to desperately ill within 24 hours. These days, we don’t hear much about it. But, since Wednesday the 5th of October is World Meningitis Day, I’m devoting this week’s newsletter to meningitis.

Image credit: Canva

Meningitis

The term ‘meningitis’ means swelling of the membrane which surrounds the brain and spinal cord. It can have many different causes. The frightening meningitis I remember hearing about as a student is more correctly known as meningococcal disease, and is caused by certain bacteria. There are also other types of meningitis caused by bacteria, but they are rarer.

Meningitis can also be caused by a number of different viruses. For example, meningitis can be caused by the measles virus, the mumps virus and the virus which causes chickenpox and shingles. Children under 5 and people with weakened immune systems are most at risk of viral meningitis.

Other types of micro-organisms, including fungi and amoebae, can also cause meningitis, although these types of meningitis are rare.

The following page from the US Centres for Disease Control gives an overview of the different causes of meningitis (2 minute read)

Meningitis | CDC

The Meningitis Foundation has information about meningitis in New Zealand, including meningococcal disease.

The Meningitis Foundation

Meningococcal disease

Meningococcal disease is caused by bacteria known as Neisseria meningitidis. These bacteria can cause symptoms other than meningitis too, including a dangerous blood infection. Around 10-20% of people who survive the disease have long-term damage, such as severe scarring, limb amputation, hearing loss and brain injury. However, the bacteria are actually quite common and most of the time they don’t cause disease at all. We don’t fully understand why the bacteria are so often harmless but sometimes cause such a dangerous disease.

Meningococcal disease is now much rarer than it was in the late 1990s and early 2000s. Over the last decade, 2019 had the highest reported number of cases, with 139 cases and 10 deaths. However, 20 years ago there were around 500-600 cases a year.

For comparison, in 2019 the USA had 375 cases reported and Australia had 383.

The bacteria which cause meningococcal disease are divided into different groups. In different parts of the world and at different times, different groups are associated with the disease. In New Zealand, groups B and C were most common from 2015-2017, for example, but from 2018, groups W and Y became more common. These groups are important, because they affect the choice of vaccine.

Here is some general information about meningococcal disease from the New Zealand Immunisation Advisory Service, including information about the different groups (5 minute read and 1 minute video).

Meningococcal disease | Immunisation Advisory Centre (immune.org.nz)

Vaccination against meningococcal disease

Because there are different groups of bacteria involved, vaccination against meningococcal disease is complicated. There is no universal meningococcal vaccine.

There are currently four vaccines available in New Zealand. These target different bacterial groups and are used for different groups of people. There is a fifth vaccine which was used during the 1990s and 2000s. It targeted a single strain of group B which was prevalent in New Zealand at the time. Now that strain has declined and others have become more prevalent, the vaccine is no longer in use.

Vaccines against meningococcal disease are only funded for specific groups of people who are at particularly high risk. To make matters more confusing, for different groups of people there are different vaccines funded. There are also groups for whom vaccination is recommended, but not funded.

I haven’t found a clear-cut explanation of why the vaccines aren’t more widely funded. However, they do not give long-lasting immunity, so I suspect that the reason is a calculation of the cost of the vaccine in proportion to the benefit over the longer term.

Summary of vaccines (6 minute read)

The best summary I’ve found of the different vaccines comes from the Meningitis Foundation. The page I have linked to below covers the four different vaccines against meningococcal disease. It also mentions pneumococcal disease, which can include meningitis. Note that the Meningitis Foundation is an advocacy group, and some of the material on their pages is advocating for the funding of vaccination.

Meningitis Foundation | Prevention | Vaccine | ACWY | Bexsero | New Zealand — The Meningitis Foundation

Individual vaccines

Information on the individual vaccines can also be found on the following pages from New Zealand’s Immunisation Advisory Service. Each page has an overview and more in-depth information which is targeted at medical professionals – you’ll need to check both to find all the details. The pages also link to other information about each vaccine.

Bexsero, vaccine against group B only (10 minute read)

Bexsero | Immunisation Advisory Centre (immune.org.nz)

NeisVac-C, vaccine against group C only, for babies (5 minute read)

NeisVac-C | Immunisation Advisory Centre (immune.org.nz)

Menactra, vaccine against groups A, C, W and Y (7 minute read)

Menactra | Immunisation Advisory Centre (immune.org.nz)

Nimenrix, vaccine against groups A, C, W and Y (6 minute read)

Nimenrix | Immunisation Advisory Centre (immune.org.nz)

Summary

In all honesty, there’s a lot of information about vaccination against meningococcal disease, and I found it fairly confusing. If you are having conversations with people about vaccination, here are the points that I think are most important to know.

• Meningococcal disease is still a threat, although it is rare.

• The age groups most at risk are children under 5, teenagers and young adults.

• Among these groups, those who have medical conditions which reduce immunity, and those living in close quarters such as residential hostels are most at risk.

• If you or your child belongs to one of the groups at greatest risk, you can talk to your doctor about whether you should consider vaccination and whether the vaccines are funded.