As with all medicines, every vaccine must go through extensive testing to ensure it is safe before it can be introduced for a broader use.
Possible side effects
Vaccines may cause some side effects. Most of these are very mild, such as pain or swelling at the injection site, headache or a low-grade fever. These side effects typically only last a couple of days and are easily treatable. Serious side effects after vaccination, such as a severe allergic reaction, are very rare and clinic staff are trained to deal with them.
Rare side effects can come to our knowledge only after a new vaccine is used on a larger number of people. This is why ongoing monitoring is important after the vaccine is introduced. For example Covid-19 adeno vector vaccine was linked to extremely rare blood clots. The use of the vaccine was re-evaluated in Finland after this new information.
Different types of vaccines
There are several different types of vaccines. This is why possible side effects might also vary according to the vaccine type. For example live, attenuated vaccines must replicate to produce an immune response. For this reason these vaccines might cause mild, sometimes disease resembling, side effects 1-2 weeks after vaccination. Subunit, recombinant, polysaccharide, and conjugate vaccines typically cause mild side effects 1-2 days after injection.
The benefits of vaccinations
Vaccines can prevent infectious diseases, serious illness and death. There are still many infectious diseases that could be prevented in the future. This is why vaccine research is important. The need for vaccination depends on a person’s general health status, age, travel plans and living conditions. The disease-prevention benefits of getting vaccines are typically much greater than the possible side effects for almost all people.