Trials in Thailand with a candidate vaccine for dengue, a potentially fatal mosquito-borne disease, have shown it to protect against three of the four virus strains, its French maker said Wednesday.
The first trials in humans proved the vaccine was safe and represented a key milestone in the quest for a dengue jab, vaccine-maker Sanofi Pasteur executive vice president Michel De Wilde said in a statement.
"This is also an important development for global public health, since there is currently no specific treatment or prevention for dengue."
The World Health Organisation says the disease infects between 50 million and 100 million people every year and kills more than 20,000 -- mainly in tropical and subtropical regions of Asia and Latin America, but expanding rapidly including to parts of Europe.
Researchers estimate that some three billion people live in regions susceptible to dengue contagion and another 20 million tourists pass through them.
The disease caused by one of four virus serotypes results in fever, aches, rashes, vomiting and in rare cases death. Children are especially vulnerable.
Sanofi Pasteur said its candidate vaccine was effective against three of the four virus serotypes and analyses were under way "to understand the lack of protection for the fourth".
The company conducted trials on 4,000 children aged four to 11 in Thailand's Muang district, the results of which have yet to be published in a peer-reviewed medical journal.
Larger Phase III trials with 31,000 adults and children are taking place in 10 countries in Asia and Latin America.