Zika Vaccine Clinical Trial Begins

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The National Institute of Allergy and Infectious Diseases began a first-in-human trial of an experimental live, attenuated Zika virus vaccine.

On Aug. 16, 2018, the National Institutes of Health (NIH) announced that vaccinations have begun in a first-in-human trial of an experimental live, attenuated Zika virus vaccine developed by scientists at the National Institute of Allergy and Infectious Diseases (NIAID), part of the NIH.


The experimental vaccine used in the trial was developed by a team of scientists led by Stephen Whitehead, PhD, of NIAID’s Laboratory of Viral Diseases.



The laboratory used genetic engineering techniques to create a chimeric virus, made by combining genes from multiple viruses. The chimeric virus consists of a dengue virus type 4 backbone (dengue is caused by any of four serotypes (related viruses) that expresses Zika virus surface proteins. NIH reports that the chimeric virus is live but attenuated, or weakened, so it cannot cause disease in recipients. When injected into the body, the weakened virus is expected to prompt an immune response. The Phase I clinical trial will analyze this response in participants and assess the safety of the experimental vaccine, which showed promise in earlier tests in rhesus macaques monkeys. Charles River Laboratories, a contract research organization,  manufactured the vaccine candidate for the Phase I clinical trial in Malvern, PA.


The trial will enroll a total of 28 healthy, non-pregnant adults ages 18 to 50 at the Johns Hopkins Bloomberg School of Public Health Center for Immunization Research in Baltimore, MD, and at the Vaccine Testing Center at the Larner College of Medicine at the University of Vermont in Burlington. NIAID is sponsoring the trial.


According to NIH, Whitehead has also developed a live, attenuated dengue vaccine candidate called TV003 designed to elicit antibodies against all four dengue virus serotypes. The experimental vaccine is currently under evaluation in a Phase III clinical trial conducted in Brazil by the Butantan Institute. Whitehead plans to develop a single vaccine that would protect against both Zika and dengue viruses. According to the Centers for Disease Control and Prevention, dengue is endemic in at least 100 countries in Asia, the Pacific, the Americas, Africa and the Caribbean. Zika virus has been found to circulate in many of these same areas. Once the Zika vaccine candidate proves safe in Phase I clinical testing, Whitehead plans to add the Zika component to the tetravalent dengue vaccine candidate and evaluate the new pentavalent candidate in a Phase I clinical trial.


No licensed vaccines for Zika virus infection are currently available. However, NIH reports that several are in various stages of development.


Source: National Institutes of Health