Sanofi Pasteur, the vaccines division of sanofi-aventis Group, announced that its investigational tetravalent dengue vaccine is entering into a paediatric clinical study in Thailand to assess the efficacy of the vaccine in protecting children against dengue, the most widespread tropical disease after malaria. Sanofi Pasteur's tetravalent dengue vaccine candidate is the first to reach this stage of clinical development.

Sanofi Pasteur is collaborating with Mahidol University of Thailand, the Ministry of Public Health, and the Pediatric Dengue Vaccine Initiative (PDVI) to conduct this efficacy study in the province of Ratchaburi.

"Large scale paediatric studies are instrumental for the development of a safe and efficacious dengue vaccine to protect against a disease that primarily affects children," said Dr Pratap Singhasivanon, Dean of the Faculty of Tropical Medicine, Mahidol University. "We are happy to contribute to an important milestone with the actual start of an efficacy study in Ratchaburi."

The Sanofi Pasteur clinical study program follows guidelines from the Initiative for Vaccine Research (IVR) led by the World Health Organization (WHO), which fosters the global efforts towards dengue vaccine development.

"WHO is committed to the availability of a dengue vaccine that will ultimately benefit children in endemic countries," said Dr. Joachim Hombach, Coordinator Implementation Research for IVR, WHO.

Sanofi Pasteur started the development of a dengue vaccine in the 90's. Clinical studies with the most advanced tetravalent candidate vaccine started in the 2000's. In a study in the United States, immunization with three doses of Sanofi Pasteur's tetravalent dengue vaccine candidate generated a sero-neutralizing antibody response against all four serotypes of the virus responsible for dengue fever in 100 per cent of adults who participated in the trial. The Sanofi Pasteur dengue vaccine research program includes ongoing clinical studies in Mexico, Peru, and The Philippines with adults and children.

Dengue fever is a mosquito-borne disease caused by four types of dengue viruses (type 1 to 4). Overall, the disease is a potential threat for almost half the world's population. Of the estimated 230 million people infected annually, two million, mostly children, develop dengue hemorrhagic fever (DHF), a severe form of the disease. DHF is a leading cause of hospitalization in South-East Asia, placing tremendous pressure on strained medical resources.

Dengue fever occurs mostly in tropical and subtropical countries and is spreading to new parts of the globe each year. The WHO has warned that the Western Pacific Region may be heading for a major dengue outbreak. Outbreaks recently have been observed in Paraguay and the Middle East. In addition, dengue affects countries such as Australia (Queensland) and the United States (Puerto Rico, Texas-Mexico border, Hawaii and the US-affiliated Pacific Islands). A substantial number of people travelling to endemic regions are also infected each year.

Sanofi Pasteur, the vaccines division of sanofi-aventis Group, provided more than 1.6 billion doses of vaccine in 2008, making it possible to immunize more than 500 million people across the globe.