Immunogenicity and Safety of a Booster Injection of Dtap-ipv//hib (pentaxim) Administered Concomitantly with Tetravalent Dengue Vaccine in Healthy Toddlers Aged 15 to 18 Months in Mexico

Background: The live, attenuated, tetravalent dengue vaccine (CYD-TDV) is licensed in a number of dengue endemic countries for individuals ≥9 years old. Before integration of any vaccine into childhood vaccination schedules, a lack of immune interference and acceptable safety when co-administered with other recommended vaccines should be demonstrated. Methods: This randomized, multi-center, Phase III trial was conducted in Mexico. Healthy toddlers (n=732) received a booster dose of a licensed pentavalent combination vaccine (diphtheria, tetanus, acellular pertussis, inactivated polio vaccine, and Haemophilus influenzae type b [DTaP-IPV//Hib]) either concomitantly or sequentially with the second dose of CYD-TDV administered as a 3-dose schedule. Antibody titers against diphtheria toxoid, tetanus toxoid and pertussis antigens were measured by enzyme-linked immunosorbent assay. Antibodies against poliovirus and dengue serotypes were measured using a plaque reduction neutralization test. Non-inferiority was demonstrated for each of the DTaP-IPV//Hib antigens if the lower limit of the 2-sided 95% confidence interval of the difference in seroconversion rates between the 2 groups (CYD-TDV – placebo) was >–10%. Safety of both vaccines was assessed. Results: Non-inferiority in immune response was demonstrated for all DTaP-IPV//Hib antigens. After 3 doses of CYD-TDV no difference was observed in the immune response for CYD-TDV between groups. There were no safety concerns during the study. Conclusion: Co-administration of the DTaP-IPV//Hib booster vaccine with CYD-TDV has no observed impact on the immunogenicity or safety profile of the DTaP-IPV//Hib booster vaccine. No difference was observed on the CYD-TDV profile when administered concomitantly or sequentially with the DTaP-IPV//Hib booster vaccine.