Dengue fever kills 20,000 people each year and hospitalizes 500,000 living in tropical and subtropical regions. Symptoms include fever (as the name suggests), aches, rash, and increased bleeding and bruising. The disease is transmitted by tropical mosquitoes that harbor one of four serotypes of the dengue virus. Though surviving a bout of dengue confers lifelong protection against one serotype, getting infected by subsequent serotypes can cause symptoms that are much more severe. There isn’t currently an approved treatment to treat dengue, but a new vaccine could change that.
After 20 years of development, French vaccine manufacturer Sanofi Pasteur recently announced the completion of second large-scale Phase 3 trial that took place in Latin America and the Caribbean. The trial used 20,875 children between the ages of 9 and 16 and reduced the risk of infection by roughly 60 percent, while incidence of severe disease warranting hospitalization was cut by 80 percent.
Though the results from this trial were promising, the vaccine did not show uniform efficacy against all serotypes. The vaccine was most effective with serotypes 3 and 4, with infection incidence reduced by 74.0 and 77.7 percent respectively. Serotype 1 was shown to be approximately 50% effective. The vaccine was least effective with serotype 2, as it reduced disease by only 42.3 percent. Serotype 2 is regarded as the most dangerous of the four varieties.
The first large-scale trial was completed earlier this year in Southeast Asia. The vaccine was administered to 10,000 children aged 2 to 14. Incidence of the disease was reduced by 56 percent, and the researchers will continue to monitor the test subjects to gather data regarding the drug’s long term effects. Severe disease requiring hospitalization decreased by 88.5%.
"For the first time ever, after 20 years of research and industrial commitment, dengue is set to become a vaccine preventable disease," Olivier Charmeil, President and CEO of Sanofi Pasteur, said in a press release. "The data generated from our comprehensive research and clinical program involving 40,000 children, adolescents and adults from 15 countries, will be submitted to the health authorities in countries where dengue is a public health priority."
The trials represent a fantastic starting point, considering this would be the first approved vaccine to prevent dengue. The researchers had hoped the vaccine would reduce incidence risk by 80 to 90 percent, but falling short of that goal—particularly with serotypes 1 and 2—could impact how it is received. They would have to weigh whether or not it would be worth it to implement the vaccine.
Sanofi is expected to begin applying for vaccine approval in early 2015. Construction has already begun on a manufacturing facility that could create 100,000 vaccines by 2016.
More details regarding Sanofi’s announcement will be made available at the annual meeting of the American Society of Tropical Medicine and Hygiene (ASTMH) in early November and will be published in a scientific journal.
[Hat tip: Andrew Pollack, New York Times]