The CDC says a new vaccine trial focused on treating Dengue Fever, a mosquito-born illness that infects over 400 million people annually, has yielded hope that the vaccine will be successful in treating the disease.
The trial, recently published in The Lancet, was administered to 10,000 Asian children by the Research Institure for Tropical Medicine in the Philippines. The children ranged in ages two to 14 and were given a series of either three CYD-TDV injections meant to treat dengue fever or three injections of a placebo.
The vaccine was found to be responsive to 56 percent of the participants, and while not as successful as researchers had hoped, this success rate is still promising.
After the first vaccination, the second was given six months later and the third six months after that. The children were followed for up to two years.
While the new vaccination did not protect all participants from dengue fever, it did prevent the onset of the most aggressive form of the illness on over 88 percent of the recipients. Since dengue fever can cause four separate viruses, researchers say that it is difficult to establish an effective vaccine that will effectively prevent the illness.
“One of the difficulties in making a dengue vaccine is that you have to cover for four different viruses at the same time,” Sharp explained. “If you are not able to do that, you risk increasing the chances of developing severe dengue.”
“The 56 percent is not as high as we would like to see it. It’s still a big step forward, but we have a way to go before we get a vaccine that is both safe and as efficacious as we would need it to be,” said Tyler Sharp, an epidemiologist who works with the dengue fever branch at the CDC.
“This vaccine has already proven to be safe,” Sharp continued. “We know that this vaccine does not lead to a risk of developing severe dengue. That is a huge step forward.”
Dr. Marcelo Laufer, an infectious disease specialist at Miami Children’s Hospital, was “not impressed” by the strength of the vaccine, but “curious to see how the vaccine would work in different populations.”
Professor of infectious disease research at the Lee Kong Chian School of Medicine at Nanyang Technological University in Singapore, Dr. Annelies Wilder-Smith stressed that a more effective vaccine is needed.
“Of course, our desire is to have a vaccine efficacy of above 90 percent,” she said.
Wilder-Smith, who authored an accompanying journal editorial, noted that other dengue vaccines are being tested, but it will take several years before those vaccines reach phase 3 trials.
Dengue fever is caused by any one of four related viruses transmitted by mosquitoes. In the United States, dengue fever is endemic in Puerto Rico, the U.S. Virgin Islands and the U.S. territories in the Pacific Ocean.