French drugmaker Sanofi, developing the first vaccine against dengue fever, said its product reduced disease cases by 60.8 percent in a large final clinical trial.
Sanofi has invested more than 1.3 billion euros ($1.7 billion) in the project, undertaking two decades of research on the world's fastest-growing tropical disease.
The final study - conducted on 20,875 children aged 9-16 across five countries in Latin America - confirmed that the vaccine was safe, provided high protection against dengue hemorrhagic fever and cut by 80 percent the risk of hospitalization, the Paris-based company said on Wednesday.
It was 42.3 percent efficient in tackling serotype 2, one of the viral disease's four strains, compared to 35 percent in a previous Asian trial on some 10,000 children, a relatively weak rate that has puzzled scientists. [ID:nL6N0PM1OV]
Overall, the findings were consistent and more reliable in the Latin American trial as it had twice as many patients as the Asian trial, said Nicholas Jackson, head of dengue research and development at Sanofi's vaccines unit Sanofi Pasteur.
"We're talking about different regions, different seasons, different demographics, and it's very important for a vaccine to perform consistently, so these results are extremely pleasing," he told Reuters in an interview.
The study was conducted in Brazil, Colombia, Mexico, Honduras and Puerto Rico. Sanofi will unveil its detailed findings at the American Society of Tropical Medicine and Hygiene's annual meeting at the beginning of November.
As in Asia, the results suggested the new vaccine acts best as an immune booster for patients with some previous exposure, and therefore may be most useful in tropical regions where dengue is common, rather than as a vaccination for tourists.
However, given how the vaccine drastically reduces the most severe cases of dengue - by close to 90 percent - many countries and patients including tourists could see the point in using it, said Guillaume Leroy, head of Sanofi's dengue vaccine project.