Vaccines are the most effective way to prevent infectious diseases. This page explains why vaccines are safe to use and how they help protect against potentially serious illness.
Why vaccines are important
Vaccination is the most important thing we can do to protect ourselves and our children against ill health. They prevent up to three million deaths worldwide every year.
Since vaccines were introduced in the UK, diseases like smallpox, polio and tetanus that used to kill or disable millions of people are either gone or seen very rarely.
Other diseases like measles and diphtheria have been reduced by up to 99.9 per cent since their vaccines were introduced.
If people stop having vaccines, it's possible for infectious diseases to quickly spread again.
How vaccines work
Vaccines teach your immune system how to create antibodies that protect you from diseases.
It's much safer for your immune system to learn this through vaccination than by catching the diseases and treating them.
Once a vaccine has taught your immune system how to fight a disease, it can often protect you for many years.
Having a vaccine also benefits your whole community through "herd immunity".
If enough people are vaccinated, it's harder for the disease to spread to those people who cannot have vaccines. For example, people who are ill or have a weakened immune system.
By making sure your own vaccinations are up-to-date, you can help protect loved ones who may be vulnerable to infectious diseases.
All vaccines go through extensive trials and testing to make sure they will not harm you or your child. A vaccine can only be approved once it has completed testing and is found to be safe.
Once a vaccine has been approved for use in the UK it's also monitored for any rare side effects by the Medicines and Healthcare products Regulatory Agency (MHRA).
Anyone can report a suspected side effect of vaccination to the MHRA through the Yellow Card Scheme.
Side effects of vaccination
Some vaccines can cause side effects. For most people these are mild and do not last long.
The most common side effects of vaccination include:
- the area where the needle goes in looking red, swollen and feeling a bit sore for several days
- babies or young children feeling a bit unwell or developing a high temperature for one or two days
Some children might also cry and be upset immediately after the injection. This is a normal response.
It's rare for anyone to have a serious allergic reaction to a vaccination. If this does happen, it usually happens within minutes.
The person who vaccinates you or your child will be trained to recognise allergic reactions and treat them immediately. With prompt treatment, you or your child will make a good recovery.
Most people are not concerned about vaccine ingredients and know that they are safe.
The main ingredient of any vaccine is a small amount of bacteria, virus or toxin that's been weakened or destroyed in a laboratory first.
This means there's no risk of healthy people catching a disease from a vaccine.
Vaccines do sometimes contain other ingredients. These ingredients can include;
- squalene oil
- pork gelatine
- egg protein
These help to make the vaccine safer and more effective and there is no evidence the ingredients are harmful in the small quantities used in vaccines.
You can read more about vaccine ingredients on the electronic medicines compendium website.
There is misleading information about vaccines circulating online. When making the decision to receive a vaccine or to have your child vaccinated, it’s important to know that vaccines:
- do not cause autism – there is no evidence of a link between the MMR vaccine and autism
- do not overload or weaken the immune system – it is safe to give children several vaccines at a time and this reduces the amount of injections they need
- do not cause allergies
- do not contain mercury
- do not contain ingredients which cause harm in such small amounts – you can speak to your doctor, however, if you have any concerns about ingredients such as egg protein or gelatine