Figures from the World Health Organization (WHO) show that there are about 50 to 100 million incidence of dengue fever every year resulting in about 22,000 deaths worldwide but despite the prevalence and associated mortality risks of the mosquito-borne disease, no vaccine is yet available to prevent dengue.
An experimental vaccine developed by Sanofi Pasteur, however, shows promise in preventing incidence of dengue-related hospitalizations and deaths albeit its efficacy in providing protection against the disease appears to be limited.
In a late stage trial of the vaccine known as CYD-TDV described in the journal The Lancet on July 11, Maria Rosario Capeding, from the Research Institute for Tropical Medicine in the Philippines, and colleagues involved 10,275 healthy children between 2 and 14 years old from across five countries in Asia, where dengue is endemic, and randomly gave them three injections of either the experimental vaccine and placebo.
The researchers administered the second vaccine six months after the first shot and the third vaccine one year after the initial vaccination. More than 28 days after receiving their third vaccination, 133 of the children who were on placebo developed dengue. Of those who were given Sanofi's experimental vaccine, on the other hand, 117 contracted the disease showing that while it offers some form of protection, CYD-TDV merely has 56 percent protective efficacy against dengue.
The researchers also noted that the vaccine only has 35 percent effectiveness against dengue type 2 virus, 50 percent effectiveness against type 1 and more than 75 percent effectiveness against types 3 and 4 of the virus.
Still, the researchers consider this to be promising regardless that the vaccine's effectiveness in the trial was not remarkable.
"Given that dengue is a major public health problem in most Asian countries the findings have the potential to have a huge impact on public health," Capeding said. "A 56% reduction, though moderate, can translate into a huge benefit for countries plagued by the disease."
The researchers, however, observed that the vaccine protected over 88 percent of the subjects from the most serious cases of the hemorrhagic fever which often leads to hospitalizations and even death suggesting that while the vaccine provides poor protection against dengue, it reduces risks for life threatening cases of the disease.
"Vaccination could reduce the incidence of symptomatic infection and hospital admission and has the potential to provide an important public health benefit," the researchers wrote.
France-based Sanofi, which invested more than $1.77 billion in the past two decades for the development of the vaccine, funded the research.
