A clinical trial on volunteers for dengue virus proved successful six months after receiving either an experimental dengue vaccine developed by scientists from the National Institutes of Health (NIH).
All 21 volunteers who received the vaccine, TV003, were protected from infection, while all 20 placebo recipients developed infection, said the study published in Science Translational Medicine.
"The findings from this trial are very encouraging to those of us who have spent many years working on vaccine candidates to protect against dengue, a disease that is a significant burden in much of the world and is now endemic in Puerto Rico," said Stephen Whitehead of NIH’s National Institute of Allergy and Infectious Diseases (NIAID).
The experimental vaccine was developed primarily by Whitehead and his colleagues at NIAID’s Laboratory of Infectious Diseases. Scientists from the U.S. Food and Drug Administration also contributed to the vaccine’s development. The candidate vaccine is made from a mixture of four live, weakened viruses targeted to each of the four serotypes.
A total of 48 healthy adult volunteers were tested at two trial sites, the University of Vermont College of Medicine, Burlington, and Johns Hopkins Bloomberg School of Public Health, Baltimore, and were randomly assigned to receive either vaccine or placebo injection.
Six months later, 41 people returned for the challenge with dengue virus. Dr. Whitehead and colleagues also developed the challenge virus used in the trial, which is a genetically modified version of a dengue-2 serotype virus isolated in the Kingdom of Tonga in 1974.
The original virus was notable for causing only mild illness. None of the 21 TV003 vaccine recipients developed viremia or any other sign of infection.
These results have encouraged officials at Brazil’s Butantan Institute to advance the TV003 vaccine into a large phase 3 efficacy trial.