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. A vaccine was developed against Ebola virus disease and research is underway on vaccines to protect against human immunodeficiency virus (HIV).

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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 cause health problems, disabilities, or death. Many diseases are now rare due to vaccination.

Vaccine effectiveness

Approved vaccines are effective at preventing disease, serious symptoms, and decreasing transmission.

Page last updated 11 Sep 2020