The world's first vaccine against dengue, developed by French drugmaker Sanofi, has shown the ability to protect against disease caused by three of four dengue virus strains in a keenly awaited clinical trial in Thailand.
Sanofi said on Wednesday the proof of efficacy was "a key milestone" in the 70-year quest to develop a viable dengue shot, adding the results also confirmed the safety profile of the vaccine candidate.
The mosquito-borne disease - also known as "breakbone fever" - is a threat to nearly 3 billion people and is caused by four different types of virus, none of which confers immunity from the others.
Sanofi's vaccine generated an antibody response for all four dengue virus types, but evidence of protection was only demonstrated against three of the four circulating in Thailand. Sanofi said researchers were carrying out analyses to understand the lack of protection for the fourth serotype.
The company's vaccine unit, Sanofi Pasteur, has already invested 350 million euros ($423 million) in a new French factory to make the three-dose vaccine and believes its product could generate 1 billion euros in yearly sales.
But uptake of the vaccine will depend on precisely how well doctors believe it can protect populations at risk in fast-expanding tropical cities from Rio to Manila, as well as travelers.
Sanofi gave no details on the level of protection in a brief statement. The full data are now being reviewed by scientific experts and public health officials, with detailed results to be published later this year.
Sanofi previously said it planned to present the findings at the annual meeting of the American Society of Tropical Medicine and Hygiene in Atlanta in November.
Large-scale late-stage Phase III clinical studies with 31,000 participants are under way with Sanofi's vaccine in 10 countries in Asia and Latin America.
'The level of alarm is extremely high,' says WHO head, calls for an emergency meeting
One person has tested positive in Denmark for the mosquito-borne Zika virus
The world is making 20 times more plastic than we did 50 years ago with the majority being dumped in the sea.
Colombia's government has signed new legislation for the regulation and legalization of cannabis to be used for medicinal purposes.
Scientists predict Earth will become increasingly hostile for mankind as it warms, with disastrous storms, floods and droughts, and rising sea levels that will consume islands and eat away at populated coasts
Hundreds of thousands of climate activists have descended on Paris ahead of the UN Climate Conference and are preparing to defy a ban on street protests joining thousands of protestors around the world.
'This is all bad news for the planet,' head of the World Meteorological Organization says
UN agency calls for urgent climate deal as hundreds of thousands fall victims to weather disasters
Fifty grams of processed meat eaten daily increases risk of colorectal cancer by 18 percent, say experts
COP21 conference aims at securing a pact on greenhouse gases that would limit global warming to two degrees Celsius over pre-industrial times.
Earth is on track for average warming of 2.7 degrees Celsius by 2100, exceeding UN's anticipation
The London Project to Cure Blindness was established a decade ago to try to reverse vision loss in patients with age-related macular degeneration
Improvement has been seen around the globe, even in the key tropical rainforests of South America and Africa
Christiana Figueres says there is 1.2 million euros deficit to cover upcoming sessions
Some of the world's major cities, most Pacific island nations are at risk of disappearing due to rising seas
Yemen forces allied to the Houthi have launched a scud missile toward southern Saudi Arabia