A potential new dengue vaccine – the first to reach phase 3 clinical testing – has demonstrated that it provides 56 percent protection against the disease in Asian children, according to a new research.

Dengue is a mosquito-borne disease that infects around 390 million people each year, of whom about 96 million suffer from symptomatic infection, researchers said. WHO estimates that the global burden of dengue has risen 30-fold over the past 50 years, with over half of the world’s population at risk of the disease.

There is no licensed vaccine available to treat or prevent dengue fever, and efforts to develop one have been complicated by the fact that dengue is caused by four distinct dengue viruses, and a vaccine must target all four serotypes (DENV 14).

This phase 3 trial took place in dengue-endemic areas across five countries in Asia, a region that accounts for over 70 percent of the global dengue burden. The study involved 10,275 healthy children aged 2 to 14 years who were randomly assigned to receive three injections of the CYD-TDV vaccine (6851) or a placebo (3424) at 0, 6, and 12 months, and followed for up to 2 years.

The researchers recorded 250 dengue cases more than 28 days after the third injection – 117 in the vaccine group and 133 in the placebo group, demonstrating an overall protective efficacy of 56.5 percent.

The vaccine also showed 88.5 percent efficacy after 3 doses against severe disease (dengue haemorrhagic fever) which leads to hospitalisation for over half a million people (mostly children) every year, and 67 percent against dengue-associated hospitalisation.

Researchers found the vaccine gave low protection (35 percent) against DENV 2, but more than 75 percent protection against DENV 3 and 4, and 50 percent against DENV 1. The vaccine was generally well tolerated.

A total of 647 serious adverse events were reported, 402 (62 per cent) in the vaccine group and 245 (38 per cent) in the placebo group.

“Our results suggest that vaccination with CYD-TDV can reduce the incidence of symptomatic dengue infection by more than half and importantly reduced severe disease and hospitalisations,” said lead author Dr Maria Rosario Capeding from the Research Institute for Tropical Medicine in the Philippines.

“This candidate vaccine has the potential to have a significant impact on public health in view of the high disease burden in endemic countries,” Capeding said.