Prophylactic Acetaminophen Reduces Antibody Response to Several Vaccine Antigens
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Administering prophylactic doses of acetaminophen at the time of vaccination and during the following 24 hours significantly reduces several vaccine antibody responses, based on the results of two consecutive randomized, controlled, open-label studies of infants at 10 health centers in the Czech Republic.
Although fever is part of the normal inflammatory response after immunization, it can be a concern for both parents and health care professionals. The prophylactic administration of antipyretic drugs thus has become routine practice. In this study, 459 healthy infants who were 9 to 16 weeks of age at the time of enrollment were randomized into two groups: (1) a treatment group that received three weight-based doses of acetaminophen beginning immediately after each vaccine dose, and (2) a control group that did not receive acetaminophen prophylaxis (or a placebo). Primary doses of ten-valent pneumococcal vaccine and a combination diphtheria/tetanus/pertussis/hepatitis B/poliovirus/3-H. influenza type b vaccine were administered to the infants at 3, 4, and 5 months of age; oral human rotavirus vaccine was administered at 3 and 4 months of age. The infants also received booster doses of the pneumococcal vaccine and the combination vaccine between 12 and 15 months of age. The primary study objective was reduction in febrile reactions of 38.0°C (approximately 100.5°F) or greater, with assessment of immunogenicity as a secondary objective.
Prophylactic administration of acetaminophen did indeed reduce the incidence of febrile reactions: for each vaccine dose, the percentage of children with a temperature of 38°C or higher was significantly lower in the treatment group (42% after primary vaccination and 36% after booster vaccination) than in the control group (66% after primary vaccination and 58% after booster vaccination). But as the authors stated, an unexpected finding was a substantial reduction in the primary antibody responses to all 10 pneumococcal conjugate vaccine serotypes as well as to 3-H. influenza type b polysaccharide, diphtheria, tetanus, and pertactin antigens. This effect persisted after booster vaccination.
The authors concluded that prophylactic administration of antipyretic drugs at the time of vaccination should not be routinely recommended without careful weighing of the expected benefits and risks.
Lancet. 2009;374(9698):1339-50.
Author: Cynthia Knapp Dlugosz, BPharm
Date: November, 2009