Clinical trials of Zika Vaccine on humans to begin soon
A Zika vaccine developed by the National Institute of Health is about to start clinical trials in humans, and the University of Maryland School of Medicine is one of just three sites in the United States tapped to evaluate the vaccine’s safety and effectiveness.
The study is part of the U.S. government response to the ongoing outbreak of Zika virus in the Americas. According to the Centers for Disease Control and Prevention, more than 50 countries and territories have active Zika virus transmission(link is external). In the United States and its territories, more than 6,400 Zika cases have been reported. Although Zika infections are usually asymptomatic, some people experience mild illness lasting about a week. However, Zika virus infection during pregnancy can cause a serious birth defect called microcephaly, as well as other severe fetal defects of the brain and other organs. There are no vaccines or specific therapeutics to prevent or treat Zika virus disease.
“A safe and effective vaccine to prevent Zika virus infection and the devastating birth defects it causes is a public health imperative,” said NIAID Director Anthony S. Fauci, M.D. “NIAID worked expeditiously to ready
a vaccine candidate, and results in animal testing have been very encouraging. We are pleased that we are now able to proceed with this initial study in people. Although it will take some time before a vaccine against Zika is commercially available, the launch of this study is an important step forward.”The investigational Zika vaccine includes a small, circular piece of DNA — called a plasmid — that scientists engineered to contain genes that code for proteins of the Zika virus. When the vaccine is injected into the arm muscle, cells read the genes and make Zika virus proteins, which self-assemble into virus-like particles. The body mounts an immune response to these particles, including neutralizing antibodies and T cells. DNA vaccines do not contain infectious material — so they cannot cause a vaccinated individual to become infected with Zika — and have been shown to be safe in previous clinical trials for other diseases.
The Phase I clinical trial, called VRC 319, is led by Julie E. Ledgerwood, D.O., chief of the VRC’s clinical trials program. A total of 80 people will be involved in the trial. They will be tracked by researchers for two years and monitored for side effects.
If the results are good, more trials will be done next year with even more volunteers. But it could be a while before the vaccine is ready for mass use. “Under ordinary circumstances it can take 10-years or more before a vaccine starts clinical testing and makes it to market,” Neuzil said. “However, I think we saw an example with Ebola, that if it’s a public health crisis we’re able to really compress those timelines and get the vaccine out sooner.”
With the threat of Zika creeping closer to home, and no way to treat or prevent the disease, scientists are scrambling to protect people. A vaccine will be a key tool, but health officials say you should focus on protecting yourself right now.
“This is just the beginning of testing, so when we think about prevention and control of Zika, we should not yet be counting on a vaccine,” said Neuzil. We really need to continue to emphasize the other prevention and control messages of mosquito control, avoiding mosquito bites, pregnant women being very careful.”
This is the second experimental Zika vaccine to head to clinical trials. The other is developed by a private pharmaceutical company, and it started clinical testing last month.
