Walter Reed starts testing Zika vaccine in humans, joining Inovio, NIAID jabs in the clinic

Walter Reed researchers test Zika vaccine. (Courtesy of Walter Reed)

In a move that illustrates the stepped-up pace of Zika vaccine development, the Walter Reed Army Institute of Research is moving into human testing for its candidate, which uses an inactivated virus to spur immunity to the disease.

It's the third Zika-fighting shot to step into the clinic in recent months, after Inovio Pharmaceuticals, which launched human trials in June, and the NIH in August.

Silver Spring, MD-based Walter Reed plans to enroll 75 adults in a Phase I trial of that Zika purified inactivated virus (ZPIV) vaccine. Some of those participants will first be vaccinated against other flaviviruses--such as yellow fever and dengue--because immunity to those viruses can trigger an outsized immune response to Zika vaccination.

Testing the vaccine this way is important for a Zika vaccine's use in the U.S. Military, institute officials said, because service members are usually vaccinated against flaviviruses before they're deployed to regions where infection is common.

The ZPIV vaccine candidate, developed by Walter Reed using the same technology applied to its Japanese encephalitis vax licensed in 2009, proved effective at fending off Zika in mice and rhesus monkeys in preclinical studies.

In June, Plymouth Meeting, PA-based Inovio beat its rivals to the punch, becoming the first to win approval to start human testing for its candidate, GLS-5700. The NIH’s National Institute of Allergy and Infectious Diseases (NIAID) followed that up in August when it enrolled 80 volunteers to test its candidate; researchers there plan to kick off Phase II trials in early 2017.

Meanwhile, India’s Bharat Biotech has Zikavac--which also uses inactivated virus--ready to be tested on humans, and all it needs is a green light from the Drug Controller General of India.

Even though Walter Reed is not the first to start clinical trials for a Zika vax, it is among the more capable of combating communicable diseases, with experience in that field dating all the way back to its foundation. To bolster its Zika effort, the institute has brought in other experts: It partnered with flavivirus vets at Sanofi Pasteur and Brazil’s Fiocruz. The collaborative effort has additional governmental assistance from the NIAID, and the Biomedical Advanced Research and Development Authority (BARDA) is contributing funding.

ZPIV shots used in Phase I trials will be produced by Walter Reed itself, while Sanofi’s vaccine branch is exploring larger scale manufacturing. The French vaccines maker will also carry out Phase II trials as funded by BARDA, and come up with a clinical development and regulatory strategy for the vax.

The NIAID will also include ZPIV in its human testing that began in August. Volunteers will first receive NIAID’s DNA vax and then ZPIV. St. Louis University, Beth Israel Deaconess Medical Center and Harvard Medical School, and Ponce Health Sciences University in Puerto Rico have also been assigned different tasks in this round of research to test the safety and immunogenicity of ZPIV.

Although it may take researchers years before an effective Zika vaccine is put on the market, the potential of that market is large; it's valued at more than $1 billion in sales, thanks to travelers who want to be protected before visiting Zika-affected areas, as well as potential vaccine campaigns in endemic areas. Takeda, Moderna and GlaxoSmithKline are also among those in the Zika vaccine R&D race.

As of November 2, a total of 3,988 travel-associated Zika infection cases in the U.S. have been reported to the CDC, and 149 cases were confirmed within the military health system.