Side effects of vaccination

-Automatic translation

Most vaccinations can cause mild side effects such as fever, redness and swelling at the injection site, temporary discomfort, and diarrhea.

All possible side effects of vaccinations are monitored very closely and whether the vaccines are the real cause.

When evaluating vaccines, the consequences of the disease being vaccinated against and the side effects of the vaccine must always be evaluated.

More about the side effects of vaccinations

• The frequency of serious side effects is generally low for vaccines that are in use in this country but can vary from country to country, even though they are the same type of vaccine.

• If the risk of disease is significant, vaccines are often used that are relatively cheap to produce but can have more or more serious side effects than newer or more complex and thus more expensive vaccines, e.g. live polio vaccines where the disease is still active and Japanese encephalitis vaccines produced in neuronal cell culture in Asia and used in routine vaccinations where the disease is endemic.

• The reasons why side effects of the same type of vaccine differ between countries may be related to different frequencies of genotypes that increase the risk of unusual immune system reactions. Consumption habits also differ between countries and are e.g. gelatin allergy varies by country.

• Abnormal reactions of the immune system to stimuli, in general, are often linked to certain genotypes of molecules that show antigens to the immune system (see HLA molecules) and can therefore differ both by country and by the origin of individuals in each country. It is known that individuals with certain HLA genotypes sometimes get more severe symptoms or are more prone to complications from certain infections (see e.g. here) and different responses of individuals to certain vaccines depending on the HLA type have been described, e.g. for influenza, measles, and hepatitis B vaccines.

• It is quite possible that such genotypes also affect the immune system's unwanted reactions to vaccines, but research on this has not yet been done, probably because of the rarity of such events.

• Live vaccines can cause symptoms that resemble those of the disease being vaccinated against but are milder than those seen during disease transmission. However, more serious symptoms can occur if such vaccines are given to persons with a severely weakened immune system, and live vaccines should therefore be avoided in very sensitive persons and during pregnancy.

• Serious side effects of vaccinations are very rare but can be seen in approx. one in every 500,000–1,000,000 vaccinations. The potential harm from vaccination is therefore many times smaller than the harm resulting from the disease that the vaccination prevents for all vaccinations that are in widespread use worldwide.

• In many countries abroad, all possible side effects of vaccinations are monitored very closely, and in Iceland, healthcare workers are obliged by law to report unusual and/or serious side effects of vaccinations to the Norwegian Medicines Agency.

• The public must let a healthcare professional e.g. healthcare providers be aware of symptoms that occur after vaccination if they are severe (e.g. the whole arm is swollen) or are defined as rare, very rare, or frequently not known in the package leaflet.

• COVID-19 vaccines are marked for special control by the Icelandic Medicines Agency, and it is particularly important to gather information about side effects in this context.