Why vaccination is safe and important
Vaccines are the most effective way to prevent infectious diseases. This page explains how vaccines work, what they contain and the most common side effects.
Be aware that anti-vaccine stories are spread online through social media.
They may not be based on scientific evidence and could put your child at risk of a serious illness.
Things you need to know about vaccines
- protect you and your child from many serious and potentially deadly diseases
- protect other people in your community – by helping to stop diseases spreading to people who cannot have vaccines
- get safety tested for years before being introduced – they're also monitored for any side effects
- sometimes cause mild side effects that will not last long – some children may feel a bit unwell and have a sore arm for 2 or 3 days
- reduce or even get rid of some diseases – if enough people are vaccinated
- do not cause autism – studies have found no evidence of a link between the MMR vaccine and autism
- do not overload or weaken the immune system – it's safe to give children several vaccines at a time and this reduces the amount of injections they need
- do not cause allergies or any other conditions – all the current evidence tells us that vaccinating is safer than not vaccinating
- do not contain mercury (thiomersal)
- do not contain any ingredients that cause harm in such small amounts – but speak to your doctor if you have any known allergies such as eggs or gelatine
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 3 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% since their vaccines were introduced.
However, if people stop having vaccines, it's possible for infectious diseases to quickly spread again.
Information:The World Health Organization (WHO) recently listed vaccine hesitancy as one of their top 10 biggest threats to global health.
Vaccine hesitancy is where people with access to vaccines delay or refuse vaccination.
Measles and mumps in England
Measles and mumps are starting to appear again in England, even though the MMR vaccine is safe and protects against both diseases.
Measles and mumps cases have nearly doubled in recent years:
Measles and mumps cases in England
This is serious as measles can lead to life-threatening complications like meningitis, and mumps can cause hearing loss.
If 95% of children receive the MMR vaccine, it's possible to get rid of measles.
However, measles, mumps and rubella can quickly spread again if fewer than 90% of people are vaccinated.
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 your immune system knows 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.
Information:Read more about herd immunity and who it protects on the Oxford University Vaccine Knowledge Project website.
Why vaccines are safe
All vaccines are thoroughly tested to make sure they will not harm you or your child.
It often takes many years for a vaccine to make it through the trials and tests it needs to pass for approval.
Once a vaccine is being used 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.
Information:Read all about how vaccines are licensed, tested and monitored on the Oxford University Vaccine Knowledge Project website.
Side effects of vaccination
Most of the side effects of vaccination 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 2 to 3 days
- babies or young children feeling a bit unwell or developing a high temperature for 1 or 2 days
Some children might also cry and be upset immediately after the injection. This is normal and they should feel better after a cuddle.
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 deal with allergic reactions and treat them immediately. With prompt treatment, you or your child will make a good recovery.
Read vaccination tips for parents, including what to expect after vaccination.
Non-urgent advice:Speak to your GP or practice nurse if:
- you're worried about you or your child having a vaccine
- you're not sure if you or your child can have a vaccine
You could also ask a health visitor any questions you have about vaccines.
What's in a vaccine?
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. It's also why you might see vaccines being called "live" or "killed" vaccines.
What's the difference between a live or killed vaccine?
Other vaccine ingredients
Vaccines sometimes contain other ingredients that make the vaccine safe and more effective.
There is no evidence that any of these ingredients cause harm when used in such small amounts.
Squalene oil (adjuvant)
Human serum albumin and recombinant albumin
A full list of any vaccine's ingredients is available on the electronic medicines compendium (emc) website.
Information:Read more about specific vaccine ingredients on the Oxford University Vaccine Knowledge Project website.
Page last reviewed: 30 July 2019
Next review due: 30 July 2022