4 strains of dengue virus major hurdle for vaccine

Bengaluru: The cumulative disease burden caused by dengue virus has reached an unprecedented level. Dr Shiv Kumar, District Health Officer (DHO), Bengaluru Urban, said that the city has reported 841 confirmed cases of dengue from nearly 400 hospitals across the city since January.

Though dengue, an acute viral infection with potential fatal complications, has been around for the last 50 years, no effective means to control the vector mosquito that causes the disease and a vaccine to beat the disease have been found.

“Multiple factors have complicated the development of a successful vaccine. The main stumbling block is that there are four strains of dengue virus, and all the four have been seen in India. A vaccine which is sufficiently potent to control all the four strains is needed, but the vaccines developed till now have been able to beat down only one of the strains and not all," explained Dr Sudha Menon, Director, Internal medicines, Fortis Hospital.

Recently, Sanofi Pasteur, the vaccines division of Sanofi, announced that Paraná State launched the first public dengue immunisation programme in the Americas, targeting to vaccinate 5,00,000 of the state’s residents this year. In addition, Brazilians can also get access to dengue vaccination in private healthcare clinics around the country.

However, French drug and vaccines giant Sanofi suffered a setback in introducing its much awaited dengue vaccine Dengvaxia in India after a top health ministry committee rejected its request to waive of additional clinical studies.

“If one is vaccinated, the risk comes down proportionately. But dengue vaccine is still in research stage. Stability of the solution is a problem," says Dr Rajesh Shetty, Medical Superintendent and consultant intensivist, Manipal Hospital.

Hopefully, in a few years the country could see its first dengue vaccination but not now, he said.

WHO was told to introduce vaccine
In April 2016, the Strategic Advisory Group of Experts (SAGE) on immunisation to the World Health Organization (WHO) recommended endemic countries to consider introduction of Dengvaxia as part of integrated disease prevention including vector control and community mobilisation.

The WHO has set the objective of reducing mortality by dengue by 50% and morbidity by 25% by 2020 in endemic countries.