1. A recombinant live, attenuated, tetravalent vaccine was effective against dengue fever in children aged 2-14 years in endemic countries in the Asia-Pacific region.
2. The serious adverse event (mainly infections and injuries) rate was approximately 1% within 28 days of vaccination. There was one vaccine-related case of acute disseminated encephalomyelitis.
Evidence Rating Level: 1 (Excellent)
Study Rundown: Almost 400 million people are infected with dengue fever every year with up to 100 million people having symptomatic infections, while nearly 70% of cases occur in the Asia-Pacific region. No vaccines or treatments currently exist to prevent infection. This study assessed a recombinant, live, attenuated, tetravalent dengue vaccine (CYD-TDV), which was well tolerated and immunogenic in previous phase 2 trials in Asia and Latin America. This phase 3 trial tested the efficacy of the dengue vaccine in five countries in the Asia-Pacific region against symptomatic and virologically confirmed dengue fever occurring more than 28 days after the third vaccine injection, regardless of serotype or disease severity. The primary endpoint was vaccine efficacy, this was achieved with efficacy just under 60%. The serious adverse event rate was approximately 1% within 28 days of vaccination. These findings showed that the novel tetravalent vaccine may have the potential to help reduce the incidence of symptomatic infection, thus providing significant public health benefit. The efficacy rate under 60% suggests that it may not provide complete individual protection. Additional benefits may come from herd immunity. With over 10,000 participants, the trial was adequately powered. The observer-masked, placebo-controlled study design also added strength.