Should we be vaccinating more people against Meningitis B in the UK?

Dr Rajeka Lazarus is co-director of the BNSSG Immunisation Group – one of Bristol Health Partners’ Health Integration Teams. She is Consultant Senior Lecturer in Infectious Diseases and Vaccinology at the University of Bristol and UK HSA Consultant in Microbiology and Infectious Diseases based at University Hospitals Bristol and Weston NHS Foundation Trust.

It is a huge relief that the Meningitis B outbreak in Kent – which has tragically claimed two lives – now appears to have passed its peak.

The outbreak has raised many important questions about vaccination. Here’s our attempt to provide some answers, based on the best evidence available.

Who is at risk of meningococcal infection?

There have been 340 to 396 cases of meningococcal disease in the UK each year since 2022.  This is much lower than the approximately 2,500 cases reported in 1999/2000, thanks to vaccinations which have been introduced since then.

The rates of meningococcal disease are highest in children under 1.

In 2024/5 there were 96 cases of Meningitis B (Men B) in people aged 16-24 compared to 56 cases in children aged 0-4. Although the numbers of cases are higher,  the rate of disease among 16 -24 year olds is lower because there are more people in this age group. This is important when we come to discuss vaccination strategies later.

What causes meningitis and who is offered vaccines to protect against it?

The recent outbreak of meningitis has been caused by meningococcal bacteria. Different types of vaccines are offered to protect against meningococcal infection (see below).

However, meningitis is also caused by other bugs. These include Streptococcus pneumoniae (pneumococcal) and Haemophilus influenza (Hib) and mumps, the rates of which have been driven down by vaccination. Vaccines against these infections are offered as part of the routine infant vaccination schedule. The pneumococcal vaccine is also offered to older adults.

Why are there different types of vaccines against meningococcal infection?

The family of bacteria that cause meningococcal infection are divided up into different groups such as A, B, C, W, Y and X. These groups are further broken down into subtypes.

Men C was the commonest cause of meningitis in babies until the introduction of the Men C vaccination in 1999.

Outbreaks in meningitis W in teenagers in 2013/14 led to the introduction of the Men ACWY vaccine for teenagers in 2015.

A vaccine against Men B (Bexsero) only became available in 2013. In 2015, this vaccine was introduced in the UK infant immunisation schedule.

Which vaccines protect against Meningitis B?

Men B consists of different subtypes. The Bexsero vaccine protects against 40% of the subtypes that cause disease in the UK. However, as Men B is now the leading cause of meningococcal infection, this still protects many babies.

The strain implicated in the outbreak in Kent was one of the strains that is protected by the Bexsero vaccine, and its use should help limit the outbreak.

This was not the case in an outbreak in an UK nursery in 2023 where children who had already received Bexsero were still infected. Testing showed that a second meningitis vaccine, Trumenba, that became available in 2017, would have been more effective in this outbreak as this covered Men B strains that Bexsero did not.

Should the Men B programme be expanded?

The tragic outbreak in Kent has understandably led to calls for expanding the Men B vaccination programme. Several factors need to be considered:

Do we have the right vaccines?

Last year there were 65 cases of Men B in those aged 16-24, but it is not known whether the subtypes that caused the infections would be covered by the available vaccines. Vaccines that cover a greater number of subtypes could be more effective.

How do we reach the right population?

Men ACWY is offered in schools and about 75% of school pupils receive the vaccine. However, undergraduate student populations are enriched by people from all around the world so offering vaccines in universities could help strengthen protection.

What will be the economic cost?

The higher rate of infection in young children and the size of this group within the population means that vaccination is cost effective. Cost effectiveness depends on how many people are affected and how many people need to be vaccinated to prevent an infection (see picture). There are many more people aged 16-24 than those aged under 1 and the rate of infection is lower, so overall we would have to vaccinate a greater number of people to prevent fewer infections.

Population A is small compared to population B. The number of people who are prone to getting infection (red circles) compared to the total number in the populations (blue circle) is higher in population A compared to population B. So, if you had 1000 vaccine doses then more cases of infection would be prevented in population A than population B as you could vaccinate everyone in population A. This means the economic cost of vaccinating population A would more s cost effective than vaccinating population B.

Changes to the vaccination programme are done in response to changes in the rates of infection and types of vaccines available. New combination vaccines that may protect against Men ACWY and B including a wider range of subtypes are in development and could be fitted into existing schedules.

However, further monitoring of this most recent outbreak and future rates of infection in young adults, alongside advances in vaccine development, are needed to ensure an effective expansion of the Men B vaccine programme.