Family Nurse Practitioner Exam

What is the most likely cause of fever in a 4-month-old after recent vaccinations?

1. The fever is likely due to the combination of the MMR and polio vaccines

2. The fever is likely due to the pertussis component of the DTP vaccine

3. The infant is probably starting a viral upper respiratory infection

4. The infant had an allergic reaction to one of the vaccines

The correct answer is: The fever is likely due to the pertussis component of the DTP vaccine

The most likely cause of fever in a 4-month-old after recent vaccinations is attributed to the pertussis component of the DTP (diphtheria, tetanus, and pertussis) vaccine. After receiving the DTP vaccine, it's common for infants to experience mild to moderate fever as a reaction to the pertussis vaccine, along with other potential side effects such as irritability and swelling at the injection site. Fever following vaccination is typically a benign response as the body is building immunity to the components of the vaccines administered. In the case of the pertussis component, the immune response can trigger a fever as the infant's body responds to the vaccine. Understanding the typical reactions to vaccines is vital for healthcare providers, especially when assessing the safety and effectiveness of vaccines in pediatric populations. This emphasizes the importance of educating parents regarding expected reactions to vaccines, including the likelihood of mild fever, which can help alleviate concerns about more serious adverse events.