More than 25,000 people die of dengue haemorrhagic fever each year. The illness is particularly common in Puerto Rico and in tourist destinations in Latin America, Southeast Asia, and the Pacific islands, according to the U.S. Centers for Disease Control and Prevention (CDC).
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“We were pleasantly surprised to see that this candidate vaccine provided complete protection in everyone who received it”, said Dr. Durbin. But two years after vaccination, children who were under the age of nine when they received the vaccine were hospitalized for dengue at a significantly higher rate than those who received the placebo. While several pharmaceutical companies from Japan, India and the United States have thrown their proverbial hats into the dengue ring, many years of trials lay ahead.
Dengue is marked by a high fever, with other symptoms including severe headaches, severe pain behind the eyes, rash and joint, muscle or bone pain.
The results were very promising and inspired “great confidence” that the vaccine will protect people in areas where dengue is endemic.
This TV003 vaccine consisted of a mixture of four live weakened viruses targeted at each of the serotypes. All of them were then infected with a genetically modified version of the dengue-2 serotype virus, a strain of the disease that usually produces only mild symptoms.
The experimental vaccine will now move to phase three, a trial including 17,000 volunteers. Eighty per cent of them developed a rash, and 20 per cent showed lower white blood cell counts, suggesting their bodies were fighting an infection.
Dr Tom Blanchard, Honorary Senior Lecturer at The University of Manchester and Fellow of the Liverpool School of Tropical Medicine and Consultant in Infectious Diseases at North Manchester General Hospital and the Royal Liverpool Hospital, will lead the project to create and test a vaccine based on a safe derivative of a pre-existing smallpox vaccine – the only disease to have been successfully globally eradicated.
Q: Why is the Zika research only now getting underway? That didn’t appear to be good enough in an earlier study of Dengvaxia in Thailand.
One of the small study’s strengths is that it was conducted in a controlled environment in the USA, far from where dengue circulates in the population.
“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”, he added.
Durbin says the methods used in this study could be the basis for developing a vaccine against the Zika virus, another mosquito-borne infection that is in the same family of viruses as dengue, in the coming months and years.
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This kind of study mimics “the closest that it can be to what may happen in natural infection”, said Dr. Nikos Vasilakis, a virologist at the University of Texas Medical Branch in Galveston, who wasn’t involved in the new work but calls the NIH shot “one of the better vaccine candidates”.
