The use of antipyretics in conjunction with childhood immunizations may be excessive. Currently, the American Academy of Pediatrics and the Advisory Committee on Immunization Practices recommend the prophylactic use of acetaminophen or ibuprofen following immunizations in children with an increased risk of febrile seizures.1 It is generally accepted that physicians recommend the use of antipyretics before childhood immunizations to prevent adverse reactions of localized pain or increased body temperature.
A recent study by Prymula and colleagues2 assessed the effect of acetaminophen on fever reduction and immunization antibody responses in infants. The study consisted of two consecutive randomized, controlled, open-label trials conducted in 10 pediatric centers in the Czech Republic. The primary immunization arm enrolled 459 infants, 9 to 16 weeks of age, and the booster arm enrolled 414 infants, 12 to 15 months of age. Both treatment arms contained two groups: one group treated with three prophylactic, weight-adjusted doses of acetaminophen (one immediately after the immunization and two additional doses every 6 hours for the first 24 hours postimmunization), and the other group did not receive acetaminophen or placebo. Caregivers were not blinded. The immunizations administered were the 10-valent pneumococcal nontypeable Haemophilus influenza protein D-conjugate vaccine (PHiD-CV) coadministered with the hexavalent diphtheria-tetanus-3-component acellular pertussis-hepatitis B-inactivated poliovirus types 1, 2, and 3-H. influenza type b vaccine (DTPa-HBV-IPV/Hib) and oral human rotavirus vaccine (HRV).
Both groups treated with prophylactic acetaminophen had 40% to 50% fewer incidences of fever ≥38°C (100°F) compared with the group not treated with acetaminophen (p <0.05).2 Fever ≥39.5°C (103°F) was uncommon in all treatment groups. No difference was seen in the rate of swelling or redness >30 mm between groups. Infants given acetaminophen had less pain and irritability reported than the control group.
Lower seroprotection rates (<4%) against H. influenza type b and most of the pneumococcal strains occurred after the primary and booster arms in the prophylaxis group. Lower antibody geometric mean concentration (GMC) rates against the H. influenza type b, diphtheria, tetanus, and pertussis antigens were observed in the group treated prophylactically with acetaminophen. Rotavirus seroprotection and antibody GMC did not vary between groups. Each treatment group had 96% exhibit seroprotective/seropositive antibody concentrations, which indicated a significant difference due to no overlap of 95% confidence intervals.2 The clinical significance of these immunological findings requires further studies to assess the immunity coverage.
Due to the low incidence of fever ≥39.5°C (103°F) in both treatment groups of this study, it seems appropriate that acetaminophen should be recommended only for children who have an increased risk of febrile seizures.2 Other trials1,3 have assessed the use of acetaminophen in reducing adverse effects related to childhood immunizations. Postimmunization adverse effects were not reduced overall. Therefore, acetaminophen prophylaxis of childhood immunizations should be reserved for children with an increased risk of febrile seizures. Further studies need to be completed to assess the impact acetaminophen and other antipyretics have on the immunogenicity of childhood vaccines.
1. Manley J, Taddio A. Acetaminophen and ibuprofen for prevention of adverse ...