The company said immunisation with its tetravalent dengue candidate vaccine generated a seroneutralising antibody response against all four serotypes of the virus responsible for dengue fever in 100 percent of adults who participated in a trial in the United States.
Outbreaks of the mosquito-borne disease in Paraguay and the Middle East, and a rise in global travel, have increased the need for effective immunization against the virus that kills about 24,000 a year, most of them children. Sanofi plans to submit the shot for approval in 2012.
``Developing a dengue vaccine has been a major challenge for over a decade,'' said Harold Margolis, director of the Pediatric Dengue Vaccine Initiative funded by the Bill & Melinda Gates Foundation. ``We believe this moves the world closer to a dengue vaccine that will be available for people who most need it.''
Dengue fever is a mosquito-borne disease affecting up to 100 million people each year and resulting in 24,000 deaths, mostly among children, according to estimates from the World Health Organization.
Symptoms include fever, chills, headache, nausea, abdominal pain and joint and muscle pain. Those infected are more likely to develop the more severe dengue hemorrhagic fever, or DHF, if they contract another of the four strains that cause it.
``One has to be very cautious when talking about immunity against dengue,'' said Pradeep Seth, a consultant for infectious diseases and former head of microbiology at the All India Institute of Medical Sciences in New Delhi. ``I'm not saying it's not possible, but one has to work out whether the immunity induced by the vaccine will protect an individual against future hemorrhagic fever.''
This form of the disease weakens blood vessels, causing spontaneous bleeding, shock and death in about 5 percent of cases.
``It's doable, but they have to ensure the person develops antibodies against all the four strains,'' Seth said.
Meantime, the Center for Vaccine Research at the University of Pittsburgh School of Medicine in US announced that it has received two federal grants totaling $4.8 million to develop a vaccine strategy for dengue fever, which is spread by mosquitoes and infects tens of millions of people a year. The U.S. Department of Defense awarded the grants to Pitt assistant professor Ted M. Ross and professor Donald Burke, who also directs the vaccine research center.
"Our goal in this project is to generate a vaccine that will provide protection against all four of the different types of dengue virus worldwide," Ross said in a news release. "A major problem in the development of effective dengue virus vaccines is the diverse strains of virus in circulation that do not readily offer cross protective immunity."