The mosquito-borne disease, also known as "breakbone fever," is a threat to nearly three billion people in the world. Although the search for a dengue vaccine has been going on for nearly 70 years, it has intensified in the past two decades.

Sanofi's reportedly successful vaccine depends on an antibody response. The positive results of the clinical trials in Thailand have already led the company to invest 350 million euros in a new factory in France.

The vaccine is expected to generate sales to the extent of a billion dollars per year. Large-scale late-stage clinical studies of the vaccine are currently underway in 10 countries across Asia and Latin America.

A recurring problem

Dengue remains a sporadic but recurrent problem for a number of countries, including India.

"The number of dengue cases has gone up in the last decade," Dr. A. C. Dhariwal, the director of the Indian government's National Vector Borne Disease Control Program (NVBDCP) told DW. "But if we talk about the case fatality rate - defined as the number of deaths per 100 cases - that has come down."

"The geographical spread of the dengue infection is also increasing. One of the main reasons is that water storage practices are allowing dengue vector aedes aegypti - which is the main vector in Delhi."

He added that there was "profuse breeding going on in various parts of the country" and there was a particularly alarming outbreak in Tamil Nadu.

Welcome news

Dr. Dhariwal welcomed the news about the Sanofi trials. "It would be an additional tool in the armory to prevent and control dengue," he said, adding that India's Department of Biotechnology was also working on a dengue vaccine.

In the meantime, he said that the government would concentrate on objective and external short term measures such as "source reduction." Reducing the number of sources for the breeding of dengue vectors is at the core of the program.

He added that a group of technical experts would decide on whether to introduce a vaccine in future on the basis of data available.