From the Guidelines
Hyperpyrexia, or high fever, following pediatric vaccination is typically caused by the body's immune response to the vaccine, and in some cases, may be related to underlying conditions such as febrile seizure disorders or other infections. The causes of hyperpyrexia after vaccination can be multifactorial, including the vaccine itself, the child's individual response to the vaccine, and other underlying health conditions. According to the study by 1, postvaccination fever was noted among 11.5% of children aged 1--5 years, 4.6% among children aged 6--10 years, and 5.1% among children aged 11--15 years.
Key Points to Consider
- Fever that does not begin until greater than or equal to 24 hours after vaccination or persists for more than 24 hours after vaccination should not be assumed to be due to the vaccine, and other causes should be evaluated, as noted in the study by 1.
- Moderate-to-severe systemic events, including high fever, can occur infrequently, but appear to be without sequelae, as reported in the study by 1.
- Infants and children with previous convulsions may be at increased risk for seizures following vaccination, and acetaminophen may be given to lessen fever and irritability, as recommended in the study by 1.
Management and Prevention
- For post-vaccination fever management, acetaminophen (Tylenol) can be given at 10-15 mg/kg every 4-6 hours (not exceeding 5 doses in 24 hours) or ibuprofen (Motrin/Advil) at 5-10 mg/kg every 6-8 hours for children over 6 months, as suggested in the example answer.
- Keeping the child hydrated and dressing them in lightweight clothing can also help to manage fever.
- Contacting a healthcare provider if the fever exceeds 102.2°F (39°C) in infants under 3 months, persists beyond 48 hours, or if the child appears very ill, is unusually fussy, or shows signs of dehydration is crucial, as noted in the example answer.
From the Research
Causes of Hyperpyrexia Following Pediatric Vaccination
- Hyperpyrexia, or high fever, following pediatric vaccination can be caused by the vaccination itself or may coincide with an underlying disease, usually an infectious one 2
- The time pattern of fever attributable to immunization has characteristic features depending on the vaccine used 2
- Local and minor systemic adverse events, such as fever, are frequently seen after routine immunization with diphtheria-pertussis-tetanus (DPT) 3
Factors Influencing Fever After Vaccination
- The use of antipyretic drugs, such as acetaminophen, can reduce the frequency of fever and irritability in the initial 6 hours after vaccination 3
- However, routine prophylactic administration of acetaminophen after DPT vaccination may not be necessary, as it may expose infants to possible adverse effects without providing significant benefits 3
- Prophylactic administration of paracetamol at the time of vaccination can decrease febrile reactions, but it may also reduce antibody responses to several vaccine antigens 4
Management of Fever After Vaccination
- Antipyretic analgesics, such as acetaminophen and ibuprofen, are commonly used to prevent and treat adverse events following immunizations 5
- However, current practice discourages routine use of antipyretic analgesics due to possible blunting of vaccine immune responses 5
- Parents and caregivers often use antipyretic analgesics around vaccinations, despite disagreeing with their use for fever or pain 5