Patient information from BMJ

MenB (meningococcal group B) vaccine

Last published:Oct 10, 2022

The MenB vaccine is given to babies in several doses. It’s designed to protect against infection with a bacteria called Neisseria meningitidis group B. This bacteria can cause fatal illnesses including meningitis.

What is meningococcal group B infection?

MenB is one of several types of meningococcal bacterial infections. It is extremely dangerous

For example, in the UK, MenB bacterial infections kill more babies and young children than any other infectious disease.

MenB infection can cause serious illnesses, including:

• meningitis and

• sepsis (a dangerously extreme reaction in the body to an infection).

The most well-known of these conditions among parents is probably meningitis. Meningitis is inflammation (swelling) of the tissues that protect the brain and spinal cord. These tissues are called the meninges.

This type of infection is not always caused by bacteria. Meningitis can also be caused by infection with a virus or, rarely, a fungus. But these types of infections are usually less serious.

Meningitis can sometimes be fatal. And people who recover are often affected for the rest of their lives. Long-term problems caused by meningitis can include:

• severe brain damage

• hearing or vision problems

• epilepsy

• problems with memory and concentration

• problems with movement and balance, and

• needing to have limbs amputated.

Who needs the MenB vaccination?

For the best protection, babies need several doses of the MenB vaccine.

Vaccination schedules might vary slightly between countries. For example, in the UK, babies have three doses of the vaccine. This happens at the ages of:

• eight weeks

• 16 weeks, and

• one year.

Is there anyone who shouldn’t have the vaccine?

Very rarely, a baby might have a severe allergic reaction to the vaccine. But the vaccination staff will have been trained to deal with this.

You should tell the medical staff giving the vaccine about any allergies your child has.

Is it safe?

The MenB vaccine is fairly new compared with many other vaccines. But it has been given to millions of children, and no safety concerns have been found.

Even so, as with all vaccines, there can be side effects in some children.

The most common side effect is that this vaccine tends to cause a fever within 24 hours. To help prevent this, or to make it less severe, it’s important to give your baby liquid paracetamol.

The medical staff giving the vaccination should give you information at your appointment about how and when to give the paracetamol to your child.

As always with liquid paracetamol, it’s important to:

• not give more than the recommended dose, and

• never give it alongside other medicines that contain paracetamol.

Other side effects of the MenB vaccine can include:

• pain, swelling, or redness where the injection was given (called the injection site)

• diarrhoea or vomiting

• crying and irritability, and

• a mild allergic reaction to the vaccine. This can cause a rash or itching.

How is the vaccination given?

The vaccine is given as an injection into your baby’s thigh, or into the upper arm in children over the age of one year.

How well does the vaccine work?

The MenB vaccine is much newer than some vaccines that have been around for a long time. So there is less evidence about it than for more established vaccines.

But the evidence so far suggests that the vaccine protects against most types of MenB bacteria, and that vaccination programmes reduce cases of meningitis and sepsis by about two thirds.