The positive results from a clinical trial investigating the development of the first dengue vaccine was welcomed by the Dengue Vaccine Initiative.
Pharmaceutical company Sanofi Pasteur reported results from the first study conducted to evaluate the efficacy of any dengue vaccine candidate against clinical dengue disease in a population naturally exposed to dengue.
Dengue vaccine development efforts have been difficult because dengue is caused by four different related viruses, known as DENV 1, 2, 3 and 4.
The results published in today's study found that Sanofi's vaccine candidate was effective against DENV 1, 3 and 4, but DENV 2 appeared to be resistant to vaccine in this trial.
The vaccine candidate, called CYD-TDV, was tested on a group of 4,002 schoolchildren in Thailand, where dengue is known to be endemic.
"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," Dr. Luiz da Silva, Director of the Dengue Vaccine Initiative, said.
"We support the progress made by Sanofi Pasteur as well as efforts by other organizations to deliver a vaccine to populations in endemic countries," Silva said.
There is no vaccine available to treat or prevent dengue fever. While vaccines have been under development since the 1940s, little progress had been made until recently.
Reported dengue cases have increased from an annual average of fewer than 300,000 cases during the 1980s to nearly 1 million per annum from 2000 to 2005.The WHO estimates that there are 50 to 100 million dengue infections a year.
"This is a dramatic increase in dengue incidence rates, and yet it's very likely that the numbers still do not reflect the full scope of the problem," Dr. Ciro de Quadros, Executive Vice President of the Sabin Vaccine Institute, said.
"An exact number is difficult to determine due to a lack of accurate diagnostic testing and common misdiagnosis," Quadros added.
The study has been published in The Lancet.