Human trials of Zika vaccine underway

Human trials to test a vaccine for the Zika virus recently began around the United States.

As the virus continues to spread, getting a vaccine to market soon is of the utmost importance to government agencies, healthcare providers, and patients. More than 32,000 cases of the virus have been reported in U.S. territories as of November 23, and 4,444 cases have been reported in the U.S. and Washington, D.C., according to the CDC.

To that end, Walter Reed Army Institute of Research (WRAIR) in Washington, D.C., started a human trial in early November that will involve 75 healthy adults. The Phase 1 trial will test the safety and immunogenicity of the purified, inactivated Zika virus vaccine called ZPIV.

“The Army has moved efficiently from recognizing Zika virus as a threat, producing ZPIV for use in animals and demonstrating its effectiveness in mice and monkeys, producing ZPIV for human testing, and now initiating clinical trials to establish its safety and build the case for subsequent efficacy trials,” said Army Col. Nelson Michael, MD, Director of WRAIR’s Military HIV Research Program (MHRP) and Zika program co-lead, in a statement.

The Army has made significant progress on the Zika vaccine in just 10 months, Michael said. Kayvon Modjarrad, MD, Zika program co-lead and Associate Director for Emerging Infectious Disease Threats at WRAIR’s MHRP, said the Army was able to move so quickly in developing, manufacturing, and testing a Zika vaccine “because of its extensive experience with this vaccine platform and longstanding investments in the understanding and mitigation of flaviviruses like yellow fever, dating back to the founding of WRAIR.”

WRAIR’s ZPIV candidate also will soon be part of an NIH trial that began in August. The NIH vaccine contains DNA that instructs volunteers’ cells to make certain Zika proteins that then illicit an immune response. As part of that study, WRAIR’s ZPIV vaccine will be given to volunteers as a booster after they receive the NIH DNA vaccine, WRAIR officials said.

Plus, three other Phase 1 trials using the ZPIV vaccine will start this year.

St. Louis University researchers will examine the optimal dose of the vaccine to be used in larger studies. The study will be conducted at SLU's Center for Vaccine Development and at a research site partnering with SLU in Puerto Rico.

"We are seeing widespread Zika in the Americas as well as Puerto Rico,” said Sarah George, MD, a flavivirus expert and Associate Professor of Infectious Diseases at SLU and the principal investigator for the study.

George likens the Zika virus to what used to happen with rubella (German measles). “Frequently, women got infected during pregnancy and didn't realize it because their symptoms were so mild. However about a third of their babies had very serious birth defects," George said. "We developed a vaccine, the MMR vaccine, that is given to children and has virtually eliminated rubella and its associated birth defects. Our hope is a Zika vaccine can accomplish the same goal. By immunizing people early, by the time they're of child-bearing age, they'd have immunity to this virus and it is possible their babies would be protected."

Meanwhile, Beth Israel Deaconess Medical Center and Harvard Medical School researchers will evaluate the safety and immune response from a compressed vaccine schedule.

And The Ambulatory Center for Medical Research, part of Ponce Health Sciences University in Puerto Rico, will examine the vaccine’s safety and immune response in participants who have already been naturally exposed to Zika or dengue viruses.