From the Guidelines
Fever is a common side effect after vaccinations in infants, typically occurring within 24-48 hours of vaccination, and can be managed with acetaminophen at a dose of 10-15 mg/kg every 4-6 hours as needed, as recommended by the Advisory Committee on Immunization Practices (ACIP) 1. The causes of post-vaccination fever in infants can be attributed to the body's immune response to the vaccine, and in some cases, may be related to other underlying conditions such as otitis media or meningitis, which should be evaluated if the fever persists for more than 24 hours or begins more than 24 hours after vaccination 1. For post-vaccine fever management, the following steps can be taken:
- Give acetaminophen (Tylenol) at a dose of 10-15 mg/kg every 4-6 hours as needed, with a typical dose for a 2-month-old infant weighing about 5 kg being about 50-75 mg per dose 1.
- Use ibuprofen (Motrin, Advil) for infants over 6 months at 5-10 mg/kg every 6-8 hours, if necessary.
- Keep the baby comfortable with light clothing, ensure adequate fluid intake through more frequent breastfeeding or formula, and monitor their temperature.
- Contact a doctor if the fever exceeds 102°F (38.9°C), lasts more than 48 hours, or if the baby seems unusually irritable, lethargic, or has decreased feeding. It is essential to note that fever is a sign that the baby's immune system is responding appropriately to the vaccine by building protection, and post-vaccine fevers are generally harmless and resolve quickly without complications 1. In cases where the infant has a history of convulsions, acetaminophen can be given to reduce the possibility of postvaccination fever, and parents should be informed of the increased risk of postvaccination seizures 1.
From the Research
Causes of Post-Vaccination Fever in Infants
- Post-vaccination fever in infants can be caused by the body's natural response to the vaccine, as part of the inflammatory process after immunization 2
- The use of certain vaccines, such as the 4CMenB vaccine, has been associated with an increased risk of post-vaccination fever in infants 3
Management of Post-Vaccination Fever in Infants
- Breastfeeding has been shown to be effective in reducing pain and fever in infants after vaccination 4
- Prophylactic paracetamol administration has been used to reduce post-vaccination fever in infants, but its use is not routinely recommended due to concerns about its impact on antibody responses 2, 3
- The American Academy of Pediatrics recommends that parents be advised to use acetaminophen (such as paracetamol) to treat fever and discomfort after vaccination, but only if the infant is experiencing significant distress 5
- Continuous temperature monitoring using abdominally implanted data loggers has been used in nonclinical animal studies to evaluate the safety of new vaccines and to determine the best time point for body temperature measurement after vaccination 6
Factors Influencing Management of Post-Vaccination Fever
- Infant age is an important factor in the management of post-vaccination fever, with younger infants being more likely to be referred to an emergency room or hospital admission for fever 5
- The timing of fever in relation to vaccination is also an important factor, with fever occurring after vaccination being less likely to result in referral to an emergency room or hospital admission 5
- The use of prophylactic paracetamol has been shown to reduce post-vaccination fever and septic screens in hospitalized preterm infants 3