Biswal S, Borja-Tabora C, Martinez Vargas L, et al. - Researchers investigated a live attenuated tetravalent dengue vaccine (TAK-003) for its efficacy, safety, and immunogenicity in healthy children aged 4–16 years. From an ongoing phase 3, randomized, double-blind trial of TAK-003 in endemic regions of Asia and Latin America (26 medical and research centres across Brazil, Colombia, Dominican Republic, Nicaragua, Panama, Philippines, Sri Lanka, and Thailand), data up to 18 months postvaccination were presented. Random assignment was performed of 20,099 participants to receive vaccine between Sept 7, 2016, and Aug 18, 2017; inclusion of 19,021 (94·6%) was performed in the per protocol analysis, and 20 071 (99·9%) in the safety set. Participants were provided either two doses of TAK-003 or two doses of placebo, 3 months apart. In timeframes beginning 30 days post-second dose, assessment of the primary endpoint (overall vaccine efficacy) was done in the first 11 months, and the secondary endpoints (efficacy by baseline serostatus, serotype, hospitalized dengue, and severe dengue) was done in the first 17 months. Achievement of the primary endpoint was noted with an overall vaccine efficacy of 80·2% (95% CI 73·3 to 85·3; 61 cases of VCD in the TAK-003 group vs 149 cases of VCD in the placebo group). They noted an overall vaccine efficacy of 73·3% (95% CI 66·5 to 78·8) in the secondary endpoint assessment timeframe. Outcomes suggested that participants well tolerated TAK-003 and showed it as efficacious against symptomatic dengue in children regardless of serostatus before immunization. Vaccine efficacy varied by individual serotypes (DENV 1, 69·8%; DENV 2, 95·1%; DENV 3, 48·9%; DENV 4, 51·0%).