Patient information from BMJ

MenB (meningococcal group B) vaccine

Last published:Oct 10, 2022

The MenB vaccine is not part of the recommended vaccination schedule for all children in the US. But this might change. In the meantime, it is recommended for some people, including those who are more at risk of infection.

The MenB vaccine is 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 some countries, 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?

The MenB vaccine is fairly new compared with some more established vaccines. There are two MenB vaccines available in the US. Depending on which one you have, you will need either two or three doses.

While some countries have added it to their vaccination schedules for babies, in the US, it is not yet recommended as part of the routine vaccination schedule for most children.

In the US, the MenB vaccination is currently recommended for:

• people aged at least 10 years old who have an increased chance of meningococcal infection

• people aged between 16 and 23 years old. 

Is there anyone who shouldn’t have the vaccine?

Very rarely, someone 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 you or 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. Acetaminophen can help to reduce fever.

If you are giving acetaminophen to a child, whether as a pill or a liquid, it’s important to:

• not give more than the recommended dose, and

• never give it alongside other medicines that contain acetaminophen.

Other side effects of the MenB vaccine can include:

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

• diarrhea or vomiting

• muscle or joint pain

• 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 the upper arm.

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.