If this is not your name, click here.
| | If this is not your name, click here. | | |
| | Contact Us | Order Now | Journals | Bookstore | Register a colleague | | |
| |  Human Clinical Trial of Dengue Vaccine Begins BETHESDA, Md -- August 9, 2010 -- After more than a decade of development at the National Institutes of Health, a vaccine to prevent infection by the mosquito-borne dengue virus has begun human clinical testing. The vaccine was developed by scientists at the National Institute of Allergy and Infectious Diseases (NIAID) and is undergoing clinical study at the Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland. "This is an important milestone for NIAID's intramural scientists in the development of a model dengue vaccine, which could potentially have a major impact in preventing dengue," said Anthony S. Fauci, MD, NIAID, Bethesda, Maryland. "With increasing infection rates and disease severity around the world and the discovery of dengue in parts of Florida, finding a way to prevent dengue infection is an important priority." Most people infected with dengue virus experience no symptoms at all or only a mild fever. Others develop flu-like symptoms, headache, and joint, and muscle pain. A smaller portion of those infected experience the more severe dengue haemorrhagic fever/shock syndrome (DHF/DSS), which can cause high fever, pain, bleeding, a drop in blood pressure, and, in some cases, coma or death. Current treatment recommendations include bed rest, drinking fluids, and taking medicine to reduce fever. The only way to prevent infection is to avoid being bitten by Aedes mosquitoes. These mosquitoes are most active during the day and thrive in urban environments, 2 factors that make them difficult to avoid. "Controlling the mosquito vector can work, but it is very expensive and difficult to sustain," said Anna Durbin, MD, Johns Hopkins. "In the long run, vaccination would be a more efficient and cost-effective approach." The new vaccine is tetravalent -- providing protection against all 4 dengue viruses. Development of the vaccine was led by Stephen S. Whitehead, PhD, and Brian Murphy, MD, NIAID's Laboratory of Infectious Diseases. The researchers started by testing 7 monovalent vaccines, each of which is designed to protect against a single dengue serotype. "Our overall strategy was to identify the best individual candidate for each serotype, based on safety and ability to induce an immune response, and to then combine those into a tetravalent vaccine," explained Dr. Whitehead. To optimise the immune response to each dengue serotype, the researchers are testing 3 different candidate combinations of the 4 monovalent vaccines. In this Phase 1 trial, study volunteers who have never been exposed to dengue were randomly assigned to receive 1of the candidate tetravalent vaccine formulations or a placebo. The candidate vaccines are live-attenuated. Evaluation of a second candidate combination vaccine has been initiated at the University of Vermont, in Burlington, Vermont, and trials of the third candidate will begin shortly thereafter at Johns Hopkins. These early clinical trials are designed to test the vaccine's safety and ability to stimulate immune responses in healthy adults aged 18 to 50 years. After a baseline assessment, participants will receive 1 dose of the assigned vaccine or placebo. At follow-up study visits over the next 6 months, the researchers will assess their health and dengue symptoms and collect blood and urine samples for analysis. After determining which tetravalent vaccine is most promising, the researchers will test that candidate in a trial in a new group of volunteers in Brazil, where dengue has become highly prevalent. The next stage of testing, a phase 2 trial, will involve more participants and will test for differences in preliminary signs of effectiveness between people who have been exposed to dengue and those who have not, as well as the need for a booster shot within a few months of the initial vaccination. "If everything goes well after that stage, we hope to start the final phase of human testing in 3 to 4 years," said Dr. Durbin.
SOURCE: National Institutes of Health
|
