What is meningitis B – and why don’t older children get the vaccine? | University of Oxford

What is meningitis B – and why don’t older children get the vaccine?

The Conversation
Manish Sadarangani, Clinical Lecturer, University of Oxford

 MeningitisAge restrictions.

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A petition calling for the meningitis B vaccine to be given to all children, at least up to age 11 years, has gained a record number of signatories following the high profile case of a two-year-old child who died from the infection and whose parents believed they should have received the vaccine. So what is meningitis B and why is the vaccine for it only given to babies under the age of one?

What is meningitis B?

Meningitis is an infection of the meninges, the lining around the brain and spinal cord. It can be caused by different bacteria and viruses, although bacterial infections are usually more serious.

One of the bacteria which causes meningitis is called Neisseria meningitidis, also known as the meningococcus. This bacteria commonly lives harmlessly in people’s throats, but can cause devastating disease if it gets into the blood or spinal fluid. There are different types of this bacteria and the most common is known as type B – what is often referred to as “meningitis B”, or MenB.

MenB most commonly affects children under the age of one, causing symptoms including fever, poor feeding, vomiting and lethargy. It can also cause septicaemia (blood poisoning), which can lead to the telltale purple rash.

In children over the age of four the disease is rare, but there’s a second peak of the disease in adolescents (although it is not as common then as it is in infants). Babies are at high risk because they do not have immune protection from antibodies – these are passed from mothers to babies which protect them for the first few months of life, but after that they are susceptible. They gradually build up immunity as they are exposed to similar bacteria in the environment. Teenagers are more likely to carry the bacteria in their throats than other age groups, which is why there is this second, smaller, peak of disease in that age group.

With early diagnosis and antibiotics, most people will make a full recovery. But around one in ten people infected will die and up to a quarter will have significant after effects, such as hearing loss, amputation, epilepsy or learning difficulties.

The new MenB vaccine

Until recently, there was no vaccine against MenB. But in September 2015, the UK was the first country in the world to introduce a new MenB vaccine – Bexsero, produced by GlaxoSmithKline – into the routine NHS childhood immunisation programme. It involves three injections, given to babies at age two months, four months and 12 months of age, which are expected to protect children until around the age of four. However, there are lots of other bacteria and viruses which can cause meningitis, and some strains of MenB are not covered by the vaccine, so this vaccine would not be able to wipe out meningitis completely.

Are there any risks from the vaccine?

Like all vaccines, the MenB vaccine can cause side effects. It has been given to over 8,000 people in clinical trials and around 1m doses have been given since it was licensed with no concerns about its safety. It is more likely to cause a fever in babies than other vaccines, and so the recommendation in the UK is that paracetamol is given at the same time. Pain at the injection site is common in older children and adults.

How did the government decide who to vaccinate?

For vaccines, the government is advised by an independent scientific group, the Joint Committee on Vaccines and Immunisation (JCVI). They recommend which immunisations should be given and to which people (children and adults) based on who is most likely to have the disease and how effective the vaccine is. They also have to consider how cost-effective vaccines are before they can make a recommendation. JCVI can only recommend use of a vaccine that is cost-effective according to rules that are set out in guidance from NICE, which advises on evidence-based care. This analysis is undertaken to ensure that health is valued in the same way across the NHS.

There were 418 laboratory confirmed cases of MenB in the UK between July 2014 and June 2015, although this will be an underestimate because many cases are not “laboratory confirmed”. The highest rates of disease are in children under one, and the second highest in children between one and four-years-old. Around 24% of the 418 cases in 2014/15 were in the first age group, and 33% in the second.

Immunisation of children under the age of one just meets the NICE cost-effectiveness criteria but extending this to “catch up” children to the age four was found unlikely to be cost-effective in the analysis.

The current immunisation programme therefore includes vaccination of children under the age of one (and born after May 1 2015) and a booster dose at 12 months to protect toddlers until the age of four when the disease is then considered rare.

Will the recommendations change?

JCVI will continue to review the impact of the programme since the UK is the first country in the world to use the vaccine routinely and plans to re-evaluate use in other age groups as new evidence emerges.

JCVI have specifically asked for more research on vaccinating teenagers – this age group is most likely to have the bacteria in the throat (usually not causing any symptoms at all). If vaccinating them gets rid of the bacteria in the throat it will not only protect them, but indirectly protect other people as it would prevent the bacteria being spread. This is one of the reasons why other vaccines against meningococcus have been so effective, but we do not know if this will happen with the MenB vaccine.

Some parents consider going private to get the vaccine, a strategy that may be on the rise. However the cost of this for many will be prohibitive. There is also a reported shortage of the vaccine – although health officials have said this will not affect those receiving the vaccine on the NHS.

This article was originally published on The Conversation. Read the original article.