How do vaccines work?

Vaccines have been very successful in reducing cases of meningitis, with thousands of lives being saved as a result

Vaccination baby letterbox
What are vaccines?

Vaccines are given to help the body’s immune system fight infection. They contain antigens, which are usually harmless, purified components of a germ that can cause disease.

How do vaccines work?

When a vaccine is given, the immune system is stimulated to produce antibodies in response to these antigens. After vaccination, if someone comes into contact with the germ itself, the body will recognise it and be able to fight it. Vaccines are usually given by injection, but can also be given as droplets into the nose or mouth.

Vaccines do not just offer protection to the person receiving them, but also help protect others in the community, particularly children, who for medical reasons cannot be immunised.

A different vaccine is needed to give protection against each different germ, and some vaccines need to be given more than once to build up enough protection.

After vaccination

  • Common symptoms that can occur following vaccination include redness and swelling around the injection site and fever
  • They are natural reactions of the body’s immune system. 
  • These symptoms will usually subside in a very short period of time
  • They are a good indicator of a successful vaccination

Are vaccines safe?


  • Before a vaccine can be licensed for use in the UK, it is thoroughly tested for its safety and effectiveness
  • Vaccines are constantly monitored to ensure that any adverse reactions and rarer side effects are recorded for further investigation

How do vaccines reach the general public?

Vaccines go through several rigorous stages of testing and approval before they are introduced into the UK schedule.

Future vaccines

It is vital that vaccine research continues, so that new ones can be developed and existing ones improved. 

Find out more about our research programme

Find out more about meningitis vaccinations

Download our vaccines factsheet

The Information Standard banner