Immunological memory and nasopharyngeal carriage in 4-year-old children previously primed and boosted with 10-valent pneumococcal non-typeable Haemophilus influenzae protein D conjugate vaccine (PHiD-CV) with or without concomitant prophylactic paracetamol
Abstract
Background: Prophylactic paracetamol (PP) was previously shown to reduce primary and booster antibody responses against the 10-valent pneumococcal non-typeable Haemophilus influenzae protein D conjugate vaccine (PHiD-CV). This study further evaluated the effect of PP on antibody persistence, immunological memory and nasopharyngeal carriage (NPC).
Results: Induction of immunological memory was shown irrespective of PP administration at primary and booster vaccination. Antibody geometric mean concentrations were lower in the PP group for serotypes 1,4, 7F and 9V.
Opsonophagocytic titres did not differ significantly between PP and NPP groups. Previous use of PP seemed to have only a minor impact on kinetics of antibody persistence.
Reduced NPC of vaccine pneumococcal serotypes and trends towards increased NPC of non-vaccine and non-cross-reactive serotypes were seen in primed groups versus the control group, with no obvious differences between PP and NPP groups. Conclusion: Regardless of whether previous PHiD-CV vaccination was given with or without PP, induction of immunological memory and persistence of PHiD-CV's impact on carriage was seen until at least 28 months post-booster vaccination.
Our study results therefore suggest that the lower immune responses after primary and booster vaccination with PP are of transient nature.