A Phase I clinical trial for a dengue virus vaccine has begun at the Johns Hopkins Bloomberg School of Public Health in Baltimore, US.

No drug treatment or vaccine exists for the virus-borne disease, which accounts for 25,000 deaths a year.

The vaccine has been developed by scientists at the National Institute of Allergy and Infectious Diseases and is designed to be tetravalent, meaning that it offers protection against all four types of dengue virus.

The trial will measure the vaccine’s safety and ability and to stimulate immune system response in healthy adults aged 18 to 30 years old.

Three candidate combinations of vaccines are being tested, and volunteers will be randomly assigned one of the candidate vaccine combination or a placebo.

The Phase II trial will involve more people and will test the effectiveness of vaccine in people who are exposed to dengue and those who are not, as well as the need for the booster shot after the initial vaccination.

The scientists plan to start the final phase of human testing in three to four years.