The latest dengue vaccine reduced the occurrence of the disease by about 80 per cent in children vaccinated compared with unvaccinated children, researchers report, according to a report by /www.sciencenews.org.
But the full picture of the vaccine's safety and effectiveness is still under study, and won't emerge for several more years.
Dengue is responsible for an estimated 390 million infections each year.
There's no cure for the viral disease, which can cause fever, aches, pain and - in severe cases - bleeding, vomiting and rapid loss of blood pressure, which can be fatal.
Young children and the elderly are especially vulnerable to developing severe disease.
The new vaccine, under development by Takeda Vaccines, is called TAK-003.
Among 12,700 children ages 4 to 16 who were given two doses of TAK-003 three months apart, 61 infections occurred, compared with 149 cases among 6,316 children not given the vaccine.
TAK-003 also reduced the occurrence of dengue cases that lead to hospitalization by 95 per cent: Of the 210 cases of dengue, there were five hospitalizations among the vaccinated children compared with 53 in the unvaccinated ones, researchers report online November 6 in the New England Journal of Medicine.
The results describe how the vaccine performed in the year after the second dose; the children, from Asia and Latin America, will continue to be followed another 3½ years.
Dengue, one of the world's most rapidly spreading mosquito-borne diseases, is gaining footholds in new areas thanks to global travel, urbanization and climate change.
Along with measures to control mosquito populations, developing a vaccine is seen as key to fighting dengue, says Derek Wallace, a physician who heads the dengue vaccine development program at Takeda Vaccines in Cambridge, Mass.
But creating a vaccine against dengue is challenging.
There are four different, but closely related, dengue viruses, labeled by number.
A person infected by dengue type 1, for example, develops antibodies to that type.
But those antibodies can conspire to make a second infection with a different dengue virus severe.
This phenomenon, called antibody dependent enhancement, "plagues vaccine development," says Scott Halstead, a virologist who has spent his career studying dengue and first described this enhancement in the 1960s.
If a vaccine doesn't produce a strong and long-lasting immune response to all four of the viruses, it could mean a later infection not only isn't protected against, but is actually made worse.
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