By Catherine Lagrange
NEUVILLE-SUR-SAONE, France (Reuters) - Sanofi SA has started producing its experimental dengue vaccine, the most advanced against the tropical disease, in a move to keep its lead over competitors ahead of the product's likely launch in 2015.
The mosquito-borne disease is a threat to nearly 3 billion people and is caused by four types of virus, none of which confers immunity from the others. Sanofi's vaccine could generate sales of over $1 billion if successful.
Guillaume Leroy, who heads the dengue vaccine project at Sanofi Pasteur, the French group's vaccine unit, told reporters the group would be able to supply 100 million doses a year.
Sanofi Pasteur, which has been working on the project for 20 years, has kick-started production ahead of receiving authorization from regulators to ensure it will be the first company to launch this type of vaccine.
Other drug companies are also working on dengue vaccines but Sanofi's product is several years ahead.
"Production time is rather long, it takes two years to produce this vaccine," said Anthony Quin, who heads Sanofi Pasteur's manufacturing site in Neuville-sur-Saone, eastern France, where the group has invested 300 million euros ($391 million).
"It was decided in 2009 to gain time to be ready to launch it in the market as soon as possible," he added on Friday.
Dengue is the world's fastest-spreading tropical disease and represents a "pandemic threat", infecting an estimated 50 million people across all continents, according to the World Health Organization (WHO).
Data released last year from a test in Thailand showed Sanofi's vaccine failed to protect against one type of dengue virus, but confirmed for the first time that a safe dengue vaccine was possible.
Making a mixed dengue vaccine containing four different virus strains can produce uneven results, underscoring the complexity of a disease that scientists have been trying to develop a vaccine against for more than 70 years.
Sanofi, however, has said it would wait for data from two late-stage trials to get a better understanding of the vaccine.
Around 45,000 people in Asia and Latin America are taking part in these tests, with results due in late 2013 and 2014.
Transmitted by the bite of female mosquitoes, dengue is occurring more widely due to increased movement of people and goods - including carrier objects such as bamboo plants and used tires - as well as floods linked to climate change.
(Writing by Elena Berton; Editing by David Holmes)