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Monday, Sep 23, 2019

Dengue researchers develop vaccine that could protect against all strain types

Only one vaccine is available for dengue currently that does not provide high degree of protection against all 4 strains. The results from animal studies were described as a ‘gamechanger’ by the scientists.

health Updated: Nov 28, 2017 16:08 IST
Malavika Vyawahare
Malavika Vyawahare
Hindustan Times, New Delhi
India suffers from a high burden of dengue cases, with over 1,40,000 reported this year alone.
India suffers from a high burden of dengue cases, with over 1,40,000 reported this year alone.(HT File Photo)

The International Centre for Genetic Engineering and Biotechnology (ICGEB) has said its dengue research team has developed a vaccine candidate that offers protection against all the four types of viruses that causes the mosquito-borne fever without increasing risk of a lethal secondary infection.

“We believe that this ICGEB designed vaccine is a game-changer,” Navin Khanna, who leads the dengue vaccine research at ICGEB, said on Monday.

“A designed virus-like particle is much better than using the conventional dengue vaccines because they have the burden of antibody-dependent enhancement,” Khanna added.

The results, that were reported at the International Vaccine Conference organised by the international nonprofit research organisation in Delhi, are based on studies in mice and macaques.

Research for a vaccine against dengue has been going on for several decades but one that is fully effective against all the four serotypes or strains of the disease – DENV-1, DENV-2, DENV-3 and DENV-4 – does not exist.

Vaccines work by triggering an immune response. In the case of dengue, some of the antibodies produced by the body of the person affected for the first time can lead to a more severe infection the next time they are exposed to a different strain of the virus.

Developing a dengue vaccine is a complicated as it is a single strand RNA virus that breeds inside the human body with a chance of contracting a more deadly dengue infection the second time.

The ICGEB candidate does not result in the production of the antibodies that would lead to disease enhancement.

Currently, the only dengue vaccine recommended by the World Health Organization is Dengvaxia, developed by Sanofi Pasteur.

The pooled phase III clinical efficacy results among at-risk populations of over 9 years old, over a 25-month period, showed that the vaccine prevented nine out of 10 severe dengue cases, eight out of 10 hospitalisations, and two out of three symptomatic cases caused by any of the four types of the virus.

According to the WHO, efficacy by serotype demonstrated in phase III showed that the vaccine is more effective against serotypes 3 and 4 (73.6% and 83.2 %, respectively) than for serotypes 1 and 2 (58.4% and 47.1%).

Several other dengue vaccine candidates are under development with a handful in India as well. Panacea Biotec, an Indian company, is set to begin clinical trials of its vaccine in humans by early 2018.

The ICGEB research is supported by the Wellcome Trust, India’s department of biotechnology and the Indo-US Vaccine Programme. Results of the latest round of tests are yet to be published.

The ICGEB team announced a tie-up with Mumbai-based Sun Pharmaceutical Industries for development of the vaccine candidate last year.

A vaccine for the mosquito-borne disease is critical to driving down the number of deaths caused by the disease and lower out-of-pocket costs of patients.

India suffers a high burden of this tropical disease and over 140,000 cases and 216 deaths have been reported this year, according to data available till November 19.

The maximum number of cases was reported from Tamil Nadu (20,141), followed by Kerala (19,543), Karnataka (15,570), Punjab (14,049), West Bengal (10,697) and Delhi (8,549).

There are no specific therapeutic options available and the treatment of dengue is primarily supportive. Prevention is currently limited to vector control measures only.

First Published: Nov 28, 2017 15:33 IST