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First-in-human trial begins for live, attenuated Zika vaccine
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The NIH announced the start of a clinical trial of an experimental live, attenuated Zika virus vaccine developed by scientists at the National Institute of Allergy and Infectious Diseases.
“If the vaccine demonstrates an acceptable safety and immunogenicity profile in participants in the United States, we would plan to advance testing to areas where Zika virus circulated,” Anna Durbin, MD, lead investigator and professor of international health at the Johns Hopkins Bloomberg School of Public Health, told Infectious Disease News.
The trial will be conducted at the Johns Hopkins Bloomberg School of Public Health Center for Immunization Research and the Vaccine Testing Center at the University of Vermont’s Larner College of Medicine. According to a news release, the trial will enroll 28 healthy, nonpregnant adults aged 18 to 50 years. Researchers will randomly assign 20 participants to receive a single subcutaneous dose of the vaccine and eight to receive a placebo.
Since 2015, pregnant women with laboratory evidence of a possible Zika virus infection have been recorded in the U.S. Zika Pregnancy and Infant Registry list. Although Zika virus commonly results in a mild illness or even no symptoms, women infected with Zika virus during pregnancy transmit the disease to their unborn child, which may result in birth defects and/or an early development of health problems. The registry, as of July 17, 2018, has recorded a total of 2,474 possible Zika-impacted pregnancies in the U.S. and the District of Columbia, with an additional 4,900 pregnancies reported from U.S. territories and freely associated states, according to the release. The CDC advises pregnant women against travel to high-risk Zika transmission areas.
The phase 1 clinical trial was designed to analyze the immune response in participants, as well as assess the safety of the vaccine, known as rZIKV/D430-713. To ensure that any detected antibodies are related to the experimental vaccine, volunteers will be excluded from the trial if they test positive for a prior flavivirus infection, including Zika, dengue or yellow fever. Participants will record their temperature at home at specified times and track it in a diary card. According to NIAID, physical examinations will occur periodically for 6 months after vaccination and blood samples will be checked for antibody development in response to the experimental vaccine.
The vaccine was engineered to express Zika virus surface proteins. According to the release, researchers used genetic engineering techniques to create a chimeric virus that, while live, is weakened and will not cause disease but should “prompt an immune response.” Lead developer Stephen Whitehead, PhD, senior associate scientist for NIAID’s Laboratory of Viral Diseases, previously developed a similar vaccine for Dengue, TV003, which is under evaluation in a phase 3 clinical trial. After safety results are provided by phase 1 clinical testing, he intends to develop a single vaccine to protect against Zika and dengue, according to the NIAID.
“This is a very early-stage vaccine,” Durbin said. “Should it look promising from a safety and immunogenicity standpoint, additional studies will need to be done but because of the decline in Zika virus circulation, a traditional phase 3 efficacy trial may not be possible.” – by Marley Ghizzone
References:
NIH. NIH begins clinical trial of live, attenuated Zika vaccine. https://www.nih.gov/news-events/news-releases/nih-begins-clinical-trial-live-attenuated-zika-vaccine. Accessed August 16, 2018.
Disclosures: Durbin is a paid consultant for Merck & Co (dengue), Roche (diagnostics) and Valneva (dengue).