Like any other drug, vaccines can actually have side effects. These effects depend on the composition of the vaccine itself. It could be, for example, local reactions at the injection point (swelling, pain, muscle stiffness) or general reactions such as hyperthermia or apathy.
Although very rare, as for any foreign substance to the body, more or less marked allergic reactions can occur.
When adverse effects are observed (whether or not they are described in the package leaflet), it is important to contact your veterinarian for them to be reported.
It is essential to remember that all the vaccines available in Europe or USA have received a marketing authorization which requires having carried out studies on efficacy, safety, security and many others and that if these vaccines are authorized is that the health benefit is much higher than the risk incurred.