RESUMO
Combination vaccines against diphtheria, tetanus and pertussis (DTP) represent the core of childhood vaccination programs. Quinvaxem, a fully-liquid, pentavalent combination vaccine containing inactivated hepatitis B (HepB), Haemophilus influenzae type b (Hib) and whole-cell pertussis (wP) antigens, and tetanus and diphtheria toxoids, has been shown to be suitable for boosting children primed in infancy with another DTwP-HepB-Hib vaccine. This single-blind, randomized, controlled study was designed to demonstrate non-inferiority of a primary vaccination course (6-10-14 week schedule) of Tritanrix HB+Hib (first dose) and Quinvaxem (second/third doses) versus three doses of Quinvaxem with respect to the seroprotection/seroconversion rates for all antigens one month after vaccination course completion. Four hundred healthy subjects eligible for the local Expanded Program on Immunization were enrolled and equally randomized to the two treatment regimens. All subjects achieved seroprotection for tetanus and Hib, all except one for diphtheria, and all except two achieved seroconversion against Bordetella pertussis. Seroprotection against hepatitis B was achieved by 97.4% of Tritanrix HB+Hib followed by Quinvaxem and 94.9% of Quinvaxem subjects. Therefore, one month after vaccination course completion, seroprotection rates (seroconversion rate for B. pertussis) of Tritanrix HB+Hib followed by Quinvaxem were non-inferior to those elicited by Quinvaxem only, thus meeting the primary objective. Adverse events were comparable between the groups and were in line with the safety profile of the vaccines. The switch of vaccine had no apparent effect on safety endpoints. Our results support the use of Quinvaxem interchangeably with Tritanrix HB+Hib in a primary vaccination course and provides further evidence for the interchangeability of pentavalent vaccines (Clinical Trials.gov registry: NCT01357720).
