From the Guidelines
Fever after vaccination is a normal and common side effect in 6-month-old babies, typically occurring 7-12 days after vaccination and lasting 1-2 days, as reported in the study by 1. The measles component of the MMR vaccine is most often associated with this adverse event, with approximately 5% of children developing a temperature of greater than or equal to 103 F (greater than or equal to 39.4 C) after MMR vaccination. Some key points to consider when managing fever in 6-month-old babies after vaccination include:
- Fevers are usually mild and self-limiting, but can be managed with infant acetaminophen (Tylenol) at a dose of 10-15 mg per kg of body weight every 4-6 hours as needed, as suggested by general pediatric guidelines, although not specifically mentioned in the provided studies 1.
- It is essential to use the measuring device that comes with the medication for accurate dosing, and to consult with a doctor if the baby's temperature exceeds 102.2°F (39°C), if the fever lasts more than 48 hours, or if the baby seems unusually irritable, lethargic, or has difficulty feeding.
- Offering extra fluids and dressing the baby in light clothing can also help manage the fever, as stated in general pediatric care principles.
- Parents should be alert to the occurrence of fever after vaccination and treat their children appropriately, as recommended by 1. However, the most recent and highest quality study 1 provides the most relevant information on this topic, and its findings should be prioritized when making clinical decisions.
From the Research
Fever after Vaccination in 6-Month-Old Infants
- Fever is a common systemic adverse event following immunization, especially in infants and young children 2.
- The perception and management of fever in infants up to six months of age can vary among pediatricians, with factors such as infant age, temperature, and recent vaccination influencing their recommendations 3.
- A study found that US pediatricians are more concerned about general fever than fever following vaccination, with a lower threshold for referring infants to the emergency room or hospital admission if they are ≤ 2 months of age or have a high temperature 3.
Management of Fever after Vaccination
- Antipyretic analgesics are commonly used to prevent and treat adverse events following immunizations, but their routine use is discouraged due to possible blunting of vaccine immune responses 4, 5.
- A study found that prophylactic use of acetaminophen or ibuprofen may reduce the incidence of adverse reactions in young infants receiving DTwP vaccine, but no benefits have been demonstrated for other vaccines currently in use 5.
- Another study found that prophylactic antipyretics can affect immune responses to vaccines, with paracetamol potentially interfering with immune responses to pneumococcal antigens and ibuprofen reducing responses to pertussis and tetanus antigens 6.