There are a handful of vaccines available for bacterial infections. These can protect against infection by the specific bacterium they have been developed for, but do not offer wider protection against other types of bacterial infection. They are not often given unless you have a weak immune system or a medical condition.
Here are some of your most frequently asked questions about vaccines – and the answers.
What is a vaccine and how do they work?
A vaccine is a medicine that prevents a specific type of bug from making you sick. They contain a dead or weakened form of the bug, which helps your body to learn what it looks like in order to identify it and attack it before it makes you sick if you encounter it in future. The bug might be a virus, like coronavirus or the flu virus, or it could be a bacterium, like the one that causes meningitis.
What is in a vaccine?
There are different ingredients in every vaccine. Some of the most common elements you might find in a vaccine include:
- A dead or weak form of the virus or bacteria to train the immune system with
- An adjuvant – this helps increase your body’s response to the infection that is being prevented.
- Preservatives, to ensure the vaccine remains effective for long enough to be administered.
- Stabilisers, to protect the vaccine as it is stored and transported before it is administered.
According to the World Health Organisation’s vaccines information, most of the ingredients on the label of a vaccine might sound unfamiliar, but they are actually naturally occurring in our body, in the environment and even in our food.
What type bacterial infections are there vaccines for?
There are only a handful of vaccines for bacterial infections, despite there being a huge number of different types of bacteria that can make you sick. Find out more about different types of bacteria and bacteria in the human body.
There are vaccines available for the following bacterial infections, some of which (including whooping cough and Haemophilus influenzae type B) are given to all children.
- Corynebacterium diphtheriae, which causes diphtheria
- Clostridium tetani, which causes tetanus
- Bordetella pertussiswhich causes pertussis or whooping cough
- Haemophilus influenzae type b, which causes a type of meningitis
- Streptococcus pneumoniae, which causes bloodstream infections, pneumonia and meningitis
- Neisseria meningitidis, which causes meningococcal disease (a form of meningitis)
- Salmonella typhi, which causes typhoid
- Mycobacterium tuberculosis, which causes tuberculosis
- Yersinia pestis, which causes bubonic plague
- Bacillus anthracis, which causes anthrax
- Vibrio cholerae, which causes cholera
There are lots of different types of bacterial illness vaccines. Some will include dead bacteria so that the body can learn to identify and attack it when it sees it, while others contain just a small piece of the bacteria called a ‘surface protein’ that is found on the outside of the cell and can be easily detected by the body’s immune system.
Some do not include any bacteria, such as the tetanus vaccine. The illness is due to the harmful chemical (called a toxin) that is produced by the bacteria. The vaccine for this illness contains a harmlessversion of that chemical so that the body can learn to eliminate the harmful version when it sees it.
If you would like to know more about bacterial vaccines, there is a technical summary of the different types of vaccine and how they work available from ScienceDirect.
What is an mRNA vaccine?
mRNA vaccines – an entirely new type of vaccine, were first seen in clinical practice as COVID-19 vaccines. They work differently to traditional vaccines and offer hope for much faster production of vaccines, even those for bacterial illnesses (remember, COVID-19 is caused by a virus).
Traditional vaccines give our body a dead or weakened sample of the bacteria that we want it to learn to identify. mRNA vaccines give our body a lab-created copy of the bacterial mRNA, which tells our own immune cells how to make the ‘spike protein’ that appears on the surface of every bacterial cell.
This teaches our immune system what to look out for, giving a similar – although much stronger – outcome to traditional vaccines.The science to create such vaccines had been in the works for 30 years prior to the COVID-19 pandemic. Scientists knew that technically it could be used to create an immune defence against any infection if they had access to mRNA from whatever caused it (the virus or bacterium). This allowed them to start testing the COVID-19 vaccine within weeks of the start of the outbreak, and also means there could be much faster access to bacterial vaccines in the future.
Why aren’t there already more bacterial vaccines?
There are lots of reasons why we only have a handful of vaccines for bacterial illnesses, such as:
- Most bacteria are harmless, and even the ones that make us sick are usually easy to fight off if you are healthy. Many of the vaccines we have are for the very worst infections and are often given to people with weakened immune systems, such as children (who should all receive the Haemophilus influenzae type b vaccine). For the rest of us, our bodies can protect us most of the time, and we usually have antibiotic medicines to help for any bad infections.
- There can be many, many different types or ‘strains’ of the same bacteria. These will often cause the same illness, but might require different vaccines, each of which might be expensive and difficult to produce.
- There are also thousands of bacterial illnesses. If we did have a vaccine for all of them, that would be an awful lot of injections or medicines (and they might need a booster each year)!
- Bacteria often change, adapting to become resistant to new treatments – as we know all too well. It can cost millions or billions of pounds to make and administer a new treatment, and with bacteria evolving so quickly that treatment may no longer work in as little as a year’s time.
You can read more about this in the New York Times article Why don’t we have vaccines against everything?
Of course, as bacteria slowly become resistant to more of our antibiotic treatments, vaccines may become more important. Find out more about antibiotic-resistant infections and what you can do to help prevent the spread.