In a clinical trial conducted by National Institute of Allergy and Infectious Diseases (NIAID) in USA, a new vaccine against the dengue virus, called TV003, was 100% effective in preventing the disease in a study involving 41 human volunteers. TV003 is a live attenuated vaccine, meaning that it is made by creating a greatly weakened version of the dengue virus.
HOW WAS THE TRIAL CONDUCTED?
First the researchers injected 21 volunteers with the experimental vaccine, and 20 other volunteers with a dummy vaccine. Six months later, they injected all 41 volunteers with a weakened, ‘challenge’ version of the dengue virus—which usually causes symptoms similar to a mild dengue infection, such as a rash.
WHAT WERE THE RESULTS?
None of volunteers vaccinated with TV003 became sick from the challenge virus or showed the virus in their blood. TV003 successfully shielded those involved in the study against a mild strain of dengue 2, the most aggressive of all the disease types. By contrast, dengue virus was found in the blood of all of the volunteers who had received the dummy vaccine and 80% of them also developed a rash.
HOW DIFFERENT IS THIS VACCINE FROM DENGVAXIA VACCINE?
There are four strains of dengue virus and symptoms become more severe each time a person is infected.So a vaccine has to protect against all four types.
-Though the trial involved a small group of 41 volunteers, but TV003 proved 100% effective and none of the volunteers developed any symptoms.
-On the other hand,Dengvaxia vaccine provides 60 % protection, which means people still get sick and develop dengue symptoms.
-Both the vaccines provide protection against all four strains of dengue virus.
-TV003 requires only a single dose compared with multiple doses of Dengvaxia.
SO, WHAT NEXT?
Since this was a small human trial, it is too early to conclude the safety and efficacy of the vaccine. Researchers say that a five-year clinical trial involving 17,000 people in Brazil is already underway but they are hopeful that there would probably be enough data by 2018 to seek regulatory approval.The methods used in the study could also be the basis for developing a vaccine against the Zika virus, another mosquito-borne virus that is in the same family as dengue.