The second phase trial of the dengue vaccine has got promising results.

"With three years of follow-up, the single-dose tetravalent dengue vaccine, TV005, was found well tolerated and immunogenic for all four serotypes in young children to adults, including people lacking previous dengue exposure," said Rashidul Haque, a senior scientist at icddr,b, at a press conference.

Researchers from icddr,b, and the Larner College of Medicine at the University of Vermont, USA are the first to study the promising dengue vaccine in Bangladesh.

The third phase trial of the vaccine will begin in India this year and Rashidul said it would be better if they would be able to do the trial jointly.

The findings come with a ray of hope at a time when Bangladesh is grappling with its most devastating dengue outbreak on record.

Meanwhile, at least seven dengue patients died while 1,903 others were hospitalised in the last 24 hours till yesterday, according to the Directorate General of Health Services.

The result of the clinical trial along with the study was published in The Lancet Infectious Diseases journal recently.

The second phase trial found the vaccine to be 100 percent effective for persons with previous exposure to any of the serotypes 1 to 3, and about 87 percent effective for serotype 4.

On the other hand, for a person with no previous dengue infection, the vaccine is 70 percent effective for Serotype 1, 99 percent for serotype 2, 94 percent for serotype 3, and 88 percent for serotype 4.

In the trial, 194 volunteers received the TV005 vaccine or placebo over three years, beginning in 2016.

"There is a ray of hope, as the vaccine seems to work. However, two to three more years are needed to get it in the market as many more things have to be done to ensure its safety," said Dr Tahmeed Ahmed, executive director of icddr,b.

"We do not have capacity to bring it to the market and a company has to come forward for its mass production," he said.

The antibody produced due to the vaccine will remain effective for three years, said Dr Firdausi Qadri, investigator from Icddr,b, adding that they would follow the data up to five years to know more about it.

Dr Firdausi also said a phase-2 B trial will be conducted on a larger population to observe the vaccine's effectiveness.