A detailed analysis of data from a mid-stage trial of Sanofi's Dengue Fever vaccine has shown that the jab is able to offer some protection against three of four serotypes of the disease.

According to the analysis, published in The Lancet, the efficacy of Sanofi's vaccine was 61.2% against dengue virus type 1, 81.9% against type 3 and 90% against type 4, but it failed to offer any protection against serotype 2.

This dragged overall efficacy down to just 30%, falling well under the 70% benchmark researchers were hoping for. 

Nevertheless, the results from the Phase IIb study, which was conducted in 4002 children aged 4 to 11 years in Thailand, are encouraging and have sparked excitement throughout the medical community.

"This is the first time in 50 years of dengue research that I have seen a vaccine that protected a large group of children from clinical disease caused by dengue viruses," said Scott Halstead, International Vaccine Institute, Seoul, Republic of Korea.

A new era?

"An effective vaccine will be a critical tool that can change the life of millions living in endemic countries. I see this success as the beginning of a new era of effective control," commented Duane Gubler, Program on Emerging Infectious Diseases, Duke-NSU Graduate Medical School, Singapore.

Dengue is a mosquito-borne disease that infects around 220 million people every year, but to date there are no specific treatments available for the disease or any vaccines to help prevent its spread.

Deutsche Bank analyst Mark Clark has reportedly forecast that Sanofi's vaccine will likely be on the market in 2015, if development is successful, and it is expected that the jab could generate sales in excess of $1 billion.