What is a common expected outcome when an infant receives the DTaP vaccine?

When an infant receives the DTaP vaccine, a common expected outcome is redness and swelling at the injection site. This local reaction is a typical response to vaccinations, signifying that the immune system is reacting to the components of the vaccine. The redness and swelling are generally mild and temporary, typically resolving within a few days.

These localized reactions indicate that the body is generating an immune response to the vaccine, which is essential for building protection against diphtheria, tetanus, and pertussis. It's crucial to understand that while some infants might develop this reaction, it usually does not require medical intervention unless accompanied by more severe symptoms, which are less common.

In contrast, severe reactions like high persistent fever above 104F or severe headache and irritability do not typically occur with the DTaP vaccine and warrant further evaluation. Similarly, while having no reaction at the injection site may occur, it is not the standard expected outcome, since local reactions are expected and indicate an effective immune response.