Vaccines and vaccine side effects

The aim of vaccination is to obtain immunity against disease without any of the risks of having the disease.

Immunity (protection against infection) is an important part of the body's defence against infectious diseases. Once you have had an infectious disease, you will often have lifelong immunity against the same disease. 

However, undergoing illness can involve great risk. Some diseases can cause serious complications or even death. 

How do vaccines work? 

The aim of vaccination is to obtain immunity without any of the risks of having the disease. Vaccination is one of the most effective forms of disease prevention available. 

This has also been proven in Norway: After the introduction of the childhood immunisation programme, the incidence of the diseases we vaccinate against has dramatically decreased, with some diseases having almost disappeared altogether. 

However, not all vaccines you get as a child will provide lifelong protection. The effect of some vaccines diminishes over time and requires booster doses in adulthood. 

How vaccines work 

During vaccination, the body is exposed to a weakened microbe, fragments of a microbe, or something that resembles the microbe. When the active substances in the vaccine meet the body's immune system, immune cells and antibodies are produced that will recognise the “real” microbe. 

When the vaccinated person’s body encounters the real microbe in the future, their immune system will provide a faster and better immune response that can prevent disease. We call this artificially acquired active immunity. 

Booster vaccines for adults 

A booster dose is recommended for the vaccine against diphtheria, tetanus, whooping cough and poliomyelitis when more than 10 years have passed since the previous vaccination. The recommendation applies to all adults, including those who do not plan to travel abroad. 

The Norwegian Institute of Public Health website contains information about the various vaccines offered in Norway and the diseases we vaccinate against. 

Side effects after vaccination 

Although vaccines are among the medicines that cause the fewest side effects, both children and adults can experience undesired effects after vaccination. Most symptoms will present within a day, but some may appear later. 

Mild side effects, such as swelling and pain at the injection site and mild fever are fairly common. This will pass within a few hours to a few days without any special treatment. 

An allergic reaction to vaccines can occur in very rare cases. The symptoms of this include hives (itchy rash, welts) all over the body and breathing problems. 

The most dangerous allergic reactions come quickly after vaccination. Therefore, you should wait at the vaccination clinic for at least twenty minutes after vaccination to check for any possible reactions. Everyone who administers vaccines has the necessary training and medication to deal with any allergic reactions. 

Other known side effects that may occur in the first few days after vaccination: 

  • Local reaction at the injection site (swelling, tenderness, redness). 
  • Mild fever, restlessness, crying, sleepiness, feeling unwell or a lack of appetite in small children. 
  • In small children, a rapidly rising fever can lead to fever cramps. Fever cramps are not dangerous, but you should contact a doctor to rule out other acute disease. 
  • Mild fever and non-specific symptoms such as malaise, headache, dizziness and general malaise in older children and adults. 
  • Non-allergic rash. 
  • Paleness, feeling unwell or fainting after vaccination is more common in older children than in infants and is almost always due to discomfort in connection with the injection and/or the situation. 

A fever greater than 39˚C and/or malaise may be a sign of a serious disease and is not necessarily a reaction to the vaccine. You should therefore always contact a doctor if you are concerned about your health or that of your child. 

Read more about vaccine side effects at the Norwegian Institute of Public Health website (in Norwegian).

The vaccination service at Helsenorge 

You can find an overview of your vaccination status on the vaccination service at Helsenorge. Here, you can: 

  • View an overview of all vaccinations that have been registered for you and any children you may have under the age of 16 
  • Print out a vaccination card in Norwegian (Bokmål) and English 

Check your vaccination status

If you have children under the age of 16, you can also see which vaccines they have received.

Vaccination guidance from The Norwegian Institute of Public Health

The vaccination guide for healthcare professionals contains information and guidelines on vaccines, vaccination, the vaccination programs in Norway, and the vaccination of specific groups.

Norsk pasientskadeerstatning (NPE)

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Content provided by Norwegian Institute of Public Health

Norwegian Institute of Public Health. Vaccines and vaccine side effects . [Internet]. Oslo: The Norwegian Directorate of Health; updated Thursday, January 27, 2022 [retrieved Sunday, June 16, 2024]. Available from:

Last updated Thursday, January 27, 2022