Vaccines are the most effective way to prevent infectious diseases.
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.
For more information on how vaccines work visit the NHS website here
For information about the MMR vaccine for children, read our MMR (measles, mumps and rubella) vaccine FAQs.