Vaccine facts

Vaccines are used worldwide as a highly effective way to protect people from contracting infectious diseases. They also help to prevent the spread of diseases in the community. Vaccines work by ‘teaching’ a person's immune system (the body’s natural defences) to defend itself against a specific disease. They mainly target diseases caused by viruses or bacteria.

The first vaccine was developed in the 18th century in the United Kingdom. It was a vaccine against smallpox, a deadly disease. Smallpox is now eradicated worldwide in humans thanks to vaccination. The last known naturally occurring case was recorded in 1977 in Somalia. 

Nowadays, there are vaccines for many diseases. Research is ongoing to develop vaccines against more diseases.

Researchers across the world are seeking to develop a vaccine to protect against novel coronavirus disease (COVID-19). A vaccine was developed against Ebola virus disease and research is underway on vaccines to protect against human immunodeficiency virus (HIV).

doctor with a vaccine
© iStock

Safety, quality and standards

Before any new vaccine can be used, it has to undergo rigorous testing. The vaccine can only be approved for use in the European Union (EU) and European Economic Area (EEA) after a scientific evaluation of the results of these tests to ensure its quality, safety and effectiveness.

This evaluation needs to show that a vaccine’s benefits in protecting people against diseases are far greater than any potential risk. The scientific experts evaluating vaccines always consider the benefits and any potential risks very carefully, in particular because vaccines are given to healthy people.

Only then, after approval, can a vaccine be manufactured, marketed and used to protect people. The vaccine is continuously monitored to ensure it remains safe and effective.

As with any medicine, some people may experience side effects from a vaccine, but these are usually mild and short-lived. They can include mild fever, or pain or redness at the injection site. Serious side effects are very rare.

Benefits of vaccinating

Vaccines prevent diseases that could otherwise cause serious health problems, permanent disability or even death.

Approval of vaccines in the European Union

Before a vaccine can be approved in the EU, it has to undergo rigorous testing by its developer...

Monitoring vaccine safety and reporting side effects

Once a vaccine is approved for use, EU/EEA national authorities and the European Medicines Agency (EMA), continually monitor side effects in people who have received the vaccine.

Vaccine effectiveness

A vaccine's ability to prevent a specific disease determines its effectiveness.

How vaccines work

Each virus and bacterium triggers a unique response in the immune system involving a specific set of cells in the blood...

Decisions on vaccines in use in different European countries

Individual European countries decide which vaccines should be part of their national vaccination programmes and funded by their national health systems.

Page last updated 11 Sep 2020