Comparison of the tolerability of an acellular pertussis-containing vaccine given as the fifth booster dose in differently primed children.

Background: In 2005, an acellular pertussis-containing DTP-IPV-Hib vaccine for infants replaced the whole-cell combination vaccine in the National Immunisation Programme of the Netherlands. From 2008 onwards, an increase in local reactions to boosters was seen in an enhanced passive reporting system of adverse events following immunisation.

Method: A cross-sectional study was conducted to assess the difference in tolerability of a DTaP-IPV booster in four-year-old children primed in infancy with either three doses DTaP-IPV-Hib (aP-primed) or three doses of DTwP-IPV-Hib (wP-primed). Parents were asked to report in a questionnaire the local reactions and systemic adverse events that developed within one week after booster administration.

Results: Children in the aP-primed group experienced significantly more local reactions (36.1% versus 58.5%; OR 2.7; 95% CI 2.2-3.3) and also more systemic events (11.0% versus 20.6%; OR 2.2; 95% CI 1.6-3.0) after the DTaP-IPV booster than wP-primed children. Besides, aP-primed children more often used acetaminophen (13.1% versus 6.7%); were more frequently absent from school, preschool, crèche or other activities (4.2% versus 1.5%), and more often had contact with the healthcare system (4.5% versus 1.6%) within one week after the booster than wP-primed children.

Conclusion: The frequency of adverse events after DTaP-IPV booster immunisation in four year old children is higher in children primed with DTaP-IPV-Hib than in children primed with DTwP-IPV-Hib. However, for primary and booster vaccinations together, immunisation with acellular pertussis combination vaccines results in fewer adverse events than vaccination of whole cell combination vaccines. So, both the effectiveness and adverse events needs consideration in the discussion with regard to optimal timing of booster dose of DTaP-IPV.