Evaluation of a Hexavalent-Pentavalent-Hexavalent Infant Primary Vaccination Series Followed by a Pentavalent Booster Vaccine in Healthy Infants and Toddlers.

Abstract

This study assessed a pediatric mixed hexavalent diphtheria (D)-tetanus (T)-acellular pertussis (aP)-inactivated poliovirus (IPV)-hepatitis B (HB)-Haemophilus influenzae b [polyribosylribitol phosphate (PRP-T)]-pentavalent (DTaP-IPV//PRP-T)-hexavalent primary series schedule followed by a pentavalent booster. Healthy infants (N = 265) who had received a prior HB vaccination received a fully liquid, hexavalent vaccine (DTaP-IPV-HB-PRP-T) at 2 and 6 months of age and a reconstituted pentavalent vaccine (DTaP-IPV//PRP-T) at 4 months of age. Coadministered vaccines were pneumococcal vaccine at 2 and 4 months (and optionally at 6 months of age), rotavirus vaccine at 2, 4, 6 months and meningococcal serogroup C vaccine at 2 months. At 18 months, participants received DTaP-IPV//PRP-T and pneumococcal vaccine boosters. Immunogenicity was assessed using validated assays and safety by parental reports. For the hexavalent and pentavalent vaccines, the primary series and booster immune responses in terms of seroprotection and vaccine response rates were high for all antigens (generally > 99% and > 95% for the primary series and booster, respectively) and prebooster antibody persistence was good for all antigens (in particular, 92.4% of participants had prebooster anti-HB antibody ≥ 10 mIU/mL). The incidence of solicited reactions was lower after the booster vaccination (56.9%-73.1%) than the primary series (76.6%-97.4%); there were few vaccine-related unsolicited adverse events (1.9% and 1.5% for the primary series and booster, respectively), none led to participant discontinuation and none was serious. This study provides data that allow recommending authorities to consider the use of a sequential hexavalent-pentavalent-hexavalent primary vaccination series followed by a pentavalent booster in coadministration with other common childhood vaccines.