By Helen Petousis Harris 30/11/2018 4


Is there a killer epidemic of meningococcal disease in NZ?

In 2018, as of November, 10 people in NZ died of meningococcal disease and six of these deaths were caused by Group W (as opposed to A, B, C, Y, and Z). Historically most deaths in NZ have been caused by Group B so this is a change. Group W has a higher fatality rate (18.2%) than B and C (7.1%).

I am starting with a simple graph that shows all the meningococcal disease cases notified in NZ since 1989. It kind of speaks for itself.

NZ Meningococcal disease notifications by year, 1989-2018* (Source ESR Meningococcal Report Nov 2018)

NZ Meningococcal disease notifications by year, 1989-2018* (Source: ESR Meningococcal Disease Report. Nov 2018)

I think the answer is no, but there does appear a small upswing. Perhaps by the end of 2018 we will land in a similar place to 2017. I have discussed in more detail here.


Is type W taking over?

Good question, and I think the answer is that we need to take W very seriously. At the moment there has been a global increase in W ST-11 (the scary super virulent one, as if meningococcal was not already horrible enough). Again I will let the graph below do the talking, note how it bounces around.

Meningococcal disease notifications by group by quarter by year, 2013-2018*

Meningococcal disease notifications by group by quarter by year, 2013-2018* Source ESR. Meningococcal Disease Report. Nov 2018.

Right now it is clear that W needs to be on the radar, it has come out of nowhere, as meningococcal does. Also note how the different groups bounce around from year to year, an upswing can disappear as quickly as it appears, like group C in 2013.


 Why are Northland getting a W vaccine and other places are not?

Simple answer – because the people there have the highest risk. Below I have simplified the number of cases of W and rate per 100,000 of Menignococcal disease in people for all the District Health Boards in NZ. A map would be better but I don’t have the software sorry.

Where

Number of W cases Rate of all meningococcal per 100,000 people
Northland 7 5.7
Bay of Plenty 1 3.9
Taranaki 0 3.4
Southern 2 3.4
Wanganui 1 3.1
Lakes 2 2.8
Counties Manukau 2 2.2
Wairarapa 0 2.2
Auckland 4 2.1
Tairawhiti 0 2.1
Waikato 0 2.0
Capital and Coast 2 1.9
Waitamata 3 1.7
South Canterbury 0 1.7
Canterbury 3 1.5
Hutt Valley 0 1.4
Nelson Marlborough 0 1.3
MidCentral 0 0.6
Hawkes Bay 0 0.0

West Coast

0

0.0

Data Source: ESR Meningococcal Disease Report. Nov 2018.

If we use 3 per 100,000 as a line in the sand for a meningococcal outbreak then 5 DHBs reach that threshold. However only Northland has had more than two cases of group W. It is mainly group B that has affected the other DHBs and A) that requires a different vaccine and B) the rate of group B is not at outbreak levels.


What about age? Why are only under five year olds and 15 to 19 year olds being offered the vaccine?

Answer: Three reasons I can think of.

Meningococcal disease notifications rate by age group, 1 Jan-16 Nov 2018.

Meningococcal disease notifications rate by age group, 1 Jan-16 Nov 2018. Source: ESR Meningococcal Disease Report. Nov 2018.

Why is there a shortage of vaccines? Surely this is bad planning.

As with any manufacturer, production needs to be planned. Confession – in a past life I was a production planner for a major cosmetic company so this all feels very familiar. Basically, the markets (in this case NZ and other countries) submit their anticipated needs for way in the future. For some vaccines this will be based on tender where we know we need enough of a certain vaccine to vaccinated our birth cohort with the scheduled vaccines. However, there is also estimating the private market demand. This can all be managed quite well. The company will schedule production accordingly and I assume allow some extra for emergency situations such as outbreaks.

Vaccines are not made in a day. It probably takes about 2-years to whip up most vaccines like these. Couple that with a limited shelf life, and the fact that unused product will need to be turfed after 2-3 years. Manufacturing enough with minimal waste, guess-timation is an inexact science and hugely challenging.

As there has been a sudden unexpected upsurge in Meningococcal W in many countries (including UK, Australia and Africa) there has been a demand for more W-containing vaccine. In NZ we normally only bring in enough for special high risk groups and the private market as we do not have this vaccine on our routine immunisation schedule. That is why we have a shortage. We could not have predicted the jump in W.

There is plenty of the Group B vaccine (Bexsero) in NZ available for private purchase. Most meningococcal in NZ is caused by group B.


4 Responses to “Killer meningococcal disease outbreak – some context”

  • Will you be using information from those using Bexsero for you research, which presumably was funded by GSK?

  • Hi there, I have a question if you don’t mind? If a carrier of meningitis receives the vaccine does that prevent them from being a carrier? Sadly we have just lost our 13mth son to meningococcal Septicaemia and I am terrified of this happening again if someone in our family is a carrier. I have asked several medical professionals and no one seems to know the answer. Please email me if you can. Many thanks

    • Hello Hannah,
      I am so very, very sorry to hear this.

      The chances of this happening again are very small but I guess not impossible. Most people carry meningococcus during their life (usually during childhood and adolescence) and it can stay in their throats for a period of weeks to months, usually not causing disease, before the body gets rid of it. This is one way natural immunity to meningococcal is developed, also through carriage of harmless bacteria that generate cross protection against meningococcal. There are several meningococcal vaccines that prevent carriage, these are called the conjugate vaccines, of which there are several brands, that cover Group A,C,W, and Y in a single vaccine. There is another vaccine that covers Group B (and probably some of the others) however the emerging evidence is that it may not be good at reducing carriage.

      The vaccine protection (and probably natural protection) against meningococcal in part relies on antibodies in the blood. After vaccination these antibodies circulate for a few years before waning. To maintain the protection a booster dose of vaccine is needed. Ideally a meningococcal vaccine could be given in infancy then early adolescence to cover the two highest risk periods. Getting the vaccine that covers the circulating groups (A,B,C,W,and Y) needs to be considered. In NZ the most common group is B followed by C and W. To optimally cover this the vaccines are Bexseronfor Group B and Menactra or Niminrix for the others.

      I hope this answers your question, let me know if you need more information.