Tetravalent dengue vaccine for children

Summary

In this phase-3 efficacy trial of a tetravalent dengue vaccine in five Latin American countries, 20,869 healthy children between the ages of 9 and 16 years were randomly assigned in a 2:1 ratio to receive three injections of recombinant, live attenuated, tetravalent dengue vaccine (CYD-TDV) or placebo at months 0, 6, and 12 under blinded conditions, and followed for 25 months. The primary outcome was vaccine efficacy against symptomatic, virologically-confirmed dengue occurring more than 28 days after the third injection. At baseline, 79.4% of an immunogenicity subgroup of 1944 children had seropositive status for one or more dengue serotypes. In the per-protocol population, there were 176 dengue cases (with 11,793 person-years at risk) in the vaccine group and 221 dengue cases (with 5,809 person-years at risk) in the control group, for a vaccine efficacy of 60.8% (95% CI 52.0%, 68.0%). Serotype-specific vaccine efficacy was 50.3% for serotype 1, 42.3% for serotype 2, 74.0% for serotype 3 and 77.7% for serotype 4. Among the severe confirmed dengue cases, 1 of 12 was in the vaccine group, for an intention-to-treat vaccine efficacy of 95.5%. Vaccine efficacy against hospitalization for dengue was 80.3%. The authors concluded that CYD-TDV dengue vaccine was efficacious against virologically-confirmed dengue infection, including severe disease.