Are vaccine side effects dangerous?

Any vaccine can cause side effects. Usually, these side effects are minor — a low-grade fever, fussiness and soreness at the injection site. Some vaccines cause a temporary headache, fatigue or loss of appetite. Rarely, a child might experience a severe allergic reaction or a neurological side effect, such as a seizure. Although these rare side effects are a concern, the risk of a vaccine causing serious harm or death is extremely small. The benefits of getting a vaccine are much greater than the possible side effects for almost all children.

Of course, vaccines aren't given to children who have known allergies to specific vaccine components. Likewise, if your child develops a life-threatening reaction to a particular vaccine, further doses of that vaccine won't be given.