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Mixed results reported on dengue vaccine
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A prevalent type of dengue in Thailand eluded a vaccine designed to prevent against it, but results of the vaccine against other serotypes show that vaccination against dengue is possible, according to study results published online.
“Our study constitutes the first-ever demonstration that a safe and effective dengue vaccine is possible. Further trials of CYD-TDV are currently underway in a number of different countries, and our hope is that the positive results of this trial will be confirmed by these larger studies, taking place in a wide range of epidemiological settings. Nearly half a million people are thought to be hospitalized with dengue every year, the majority of which are children, so the development of a safe and effective vaccine has the potential to make a hugely positive impact,” Derek Wallace, MBBS, told Infectious Diseases in Children.
Researchers from Sanofi-Pasteur reported results of a study that was conducted in 4,002 children aged 4 to 11 years, in partnership with the Mahidol University under the patronage of the Thai Ministry of Public Health. Sanofi-Pasteur’s dengue vaccine candidate is a live-attenuated vaccine. The vaccination schedule is three doses given 6 months apart, at 0, 6 and 12 months.
The full analysis of vaccine efficacy against each serotype, in an intent-to-treat analysis, showed vaccine efficacy to be 61.2% against dengue virus type 1, 81.9% against type 3 and 90% against type 4. Serotype 2 eluded the vaccine, researchers said. Analyses are ongoing to understand the lack of protection for serotype 2 in the particular epidemiological context of Thailand.
“While there is still much work to be done, these clinical trials mark a decisive step forward in the development of a safe and effective vaccine,” said Luiz da Silva, director of the Dengue Vaccine Initiative, said in a press release. “We support the progress made by Sanofi-Pasteur, as well as efforts by other organizations, to deliver a vaccine to populations in endemic countries.”
A feature of dengue epidemiology is that the relative prevalence of virus types in a given area is evolving with time. Phase 3 clinical studies of Sanofi-Pasteur’s dengue vaccine candidate are under way, with 31,000 children and adolescents in 10 countries in Asia and Latin America. These studies will generate important additional data in a broader population and in a variety of epidemiological settings to define the best conditions to set up vaccination programs to protect people at risk for dengue.
The FDA has granted fast-track designation to Sanofi’s investigational dengue vaccine. The FDA fast-track designation recognizes that a dengue vaccine would address an important unmet medical need for serious disease.
Disclosure: The study was funded by Sanofi-Pasteur.
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