A tetravalent dengue vaccine reduced symptomatic and asymptomatic dengue infection in Asian and Latin American children aged 2-16 years, according to Gustavo Olivera-Botello, PhD, and his associates at Sanofi Pasteur.
They analyzed data from 3,736 individuals in two phase III clinical trials. Patients received either the dengue vaccine CYD-TDV or placebo at month 0, month 6, and month 12, and had immunologic results from months 13 to 25. The seroconversion rate in individuals with virologically confirmed dengue between 13 and 25 months after vaccination was 88% in the vaccine group, and 98% in the placebo group.
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In individuals without virologically confirmed dengue, 219 of 2,485 participants in the vaccine group and 157 of 1,184 in the placebo group seroconverted during months 13-25. Total vaccine efficacy against asymptomatic dengue was 33.5%, and was higher in children aged 9-16, with vaccine efficacy at 38.6%.
“Since about 80% of DENV [dengue virus] infections are asymptomatic, it is likely that they contribute significantly to viral transmission to mosquitoes and thus to other human hosts. Consequently, providing simultaneous protection against both asymptomatic and symptomatic infections could contribute to reduced transmission and thus to indirect protection if the vaccine coverage rates are sufficient,” the investigators wrote.
Find the full study in the Journal of Infectious Disease (doi: 10.1093/infdis/jiw297)