Dengue vaccine could cause severe illness: Study

A new study has revealed that the first vaccine marketed to prevent dengue fever could be making people sick. The authors have urged public health officials to consider carefully which individuals need vaccination, to prevent severe illness.

An estimated 400 million people globally had been infected each year with dengue fever, a mosquito-borne virus most often found in tropical regions. People living in dengue-prone areas frequently were infected at least once, but most suffered relatively mild symptoms, including fever.

However, over 2 million people each year developed a severe haemorrhagic case of the disease, which could be fatal.

Dengue proves to be more severe during the infection. There are about 25,000 deaths as a result of the infection.

The approval of Sanofi-Pasteur's Dengvaxia, the first and only vaccine against dengue had generated much excitement.

Clinical trials involving large number of children between the ages of 2 to 14 were conducted in Southeast Asia and in Latin America, while phase three trials involved about 21,000 youngsters between the ages of 9 and 16.

The researchers found that the vaccine, reduced the number of infections by 60 per cent and hospitalisations by 80 per cent.

But as time passed, many of the vaccinated children, took seriously ill with dengue.
 
Meanwhile, dengue cases have surged in recent years, with 390 million people estimated to be infected each year, and the disease is spreading globally with cases reported in over 100 countries worldwide.

Trials showed the vaccine was 59.2 per cent effective against dengue when results were pooled across populations and age groups. However, this varied when looking at the type of dengue, the age of those receiving the vaccine and whether people had been previously infected.

"It's effectiveness depends on the local epidemiology of dengue and how intense the transmission is," said Neil Ferguson, director of the MRC Center for Outbreak Analysis and Modeling at Imperial College London, CNN reported. "If you vaccinate people at high risk and in the right age group, you can get significant benefits."