No abstract

Aim: Combining paediatric vaccines is a rational solution to reduce the number of injections during a single clinical visit, to maintain parents' compliance and to extend vaccine coverage. Different diphtheria, tetanus and whole cell pertussis (DTwP)‐containing combination vaccines are licensed and used world‐wide. This study assessed the immunogenicity and safety in infants of a combined diphtheria‐tetanus‐whole cell pertussis‐Haemophilus influenzae type b‐CRM197 conjugate full liquid vaccine. Methods: The safety and efficacy of a combined ready‐to‐use liquid vaccine containing diphtheria and tetanus toxoids, cell suspension of Bordetella pertussis and H. influenzae type b‐CRM197 conjugate vaccine (DTwPHib) were assessed in infants eligible for the local Expanded Programme on Immunization (EPI) in Valencia, Spain. The comparative group received separate injections of reference vaccines DTwP + Hib. Results: Local and systemic reactions and adverse events were generally mild and similar in the two groups. DTwPHib elicited anti‐PRP antibody titres ±0.15 μg ml−1 in 97% and DTwP + Hib in 94% of infants. Furthermore, 89% of DTwPHib and 78% of DTwP + Hib recipients attained anti‐PRP antibody titres ±1.0 μg ml−1, signifying long‐term protection. The anti‐PRP geometric mean titre was significantly higher in the combined DTwPHib vaccine group (6.65 vs 3.57 μg ml−1). In both groups, 99% of infants achieved protective (±0.01 IU ml−1) anti‐diphtheria antibody levels and all children achieved protective (±0.1 IU ml−1) anti‐tetanus antibody levels. DTwPHib caused a ±2‐fold increase in anti‐pertactin antibody titres in 91% and a ±4‐fold increase in 82% of recipients. The corresponding proportions in the DTwP + Hib group were 95% and 90%. DTwPHib induced a ±2‐fold increase in anti‐Agg 12 and 3 antibody levels in 79% and a ±4‐fold increase in 73% of recipients. The corresponding proportions among DTwP + Hib infants were 85 and 82%. Conclusion: Overall, the combined liquid vaccine DTwPHib is a safe and effective immunogenic vaccine for EPI use in infants.