Final answer:
The most appropriate action is to withhold the vaccination due to the infant's previous adverse reaction.
Step-by-step explanation:
The most appropriate action in this scenario is to withhold the vaccination. The infant developed a temperature after the previous DTaP vaccination, indicating a possible adverse reaction. It is important to monitor for any adverse reactions after vaccines and provide appropriate medical intervention if needed. Withholding the vaccination is a precautionary measure to ensure the safety of the infant.