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Tetravalent dengue vaccine safe, effective in Latin American children
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A tetravalent dengue vaccine was effective against severe virologically confirmed dengue and significantly reduced the risk for hospitalization from the disease in five Latin American countries, according to recent study findings.
Twin phase 3 clinical trials were initiated in Latin America and Asia to assess the efficacy of three doses of a recombinant, live, attenuated, tetravalent dengue vaccine (CYD-TDV, Sanofi Pasteur) given to patients with symptomatic, virologically confirmed dengue. Vaccinations were administered at 0, 6, and 12 months of the study.
Preliminary results from the Asian trial with children aged 2 to 14 years have demonstrated an overall vaccine efficacy of 56.5% after three injections, which increased to 80.8% efficacy against severe dengue, according to study researcher Luis Villar, MD, of the Universidad Industrial de Santander, Colombia, and colleagues. In addition, after 25 months of surveillance, there has been no substantial safety concerns associated with CYD-TDV.
In the current Latin American study, researchers randomly assigned 20,869 children aged 9 to 16 years to either three injections of CYD-TDV or placebo at months 0, 6, and 12. The researchers then followed the participants for 25 months.
CYD-TDV demonstrated an efficacy of 60.8% (95% CI, 52-68) against symptomatic virologically confirmed dengue among children who received three injections, and 64.7% among those who received at least one injection (95% CI, 58.7-69.8).
In addition, CYD-TDV exhibited an efficacy of 95.5% in preventing severe dengue and 80.3% efficacy in preventing hospitalization. Serotype-specific vaccine efficacy was 50.3% for serotype 1, 42.3% for serotype 2, 74% for serotype 3 and 77.7% for serotype 4.
The safety profile for CYD-TDV was considered similar to that of placebo, with no discernable difference in adverse event rates.
“The estimated efficacy between injections suggests that some protection may be provided by the first injection,” Villar and colleagues wrote. “However, the second and third vaccinations increased antibody responses in the children without previous exposure to dengue, which might also have increased the quality of the antibody response and the duration of protection.
“Planned investigations of the mechanisms of protection afforded by CYD-TDV in regions where the disease is endemic may improve our understanding of the contribution of each dose to protection.”
Disclosure: Villar reports no relevant financial disclosures. Several of the researchers report being employees of Sanofi Pasteur, which sponsored the study.
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