Vaccination is safe and side effects from a vaccine are usually minor and temporary, such as a sore arm or mild fever, depending on the type of vaccine. More serious side effects are possible, but extremely rare.
Any licensed vaccine is rigorously tested across multiple phases of trials before it is approved for use, and regularly reassessed once it is introduced. Scientists are also constantly monitoring information from several sources for any sign that a vaccine may cause health risks. (WHO)
Read more :Regulation and quality control of vaccines (who.int)