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Experts Identify Challenges to Fast-Track Development of Zika Vaccine

September 30, 2016
Past Army-led vaccine development efforts could inform path for WRAIR ZPIV candidate

Zika vaccine development is advancing rapidly thanks to cross-sector research and development collaboration along with promising preclinical findings that demonstrate an effective vaccine is feasible.

However, to maintain this momentum and ultimately develop, license, and deploy a vaccine capable of impacting the current epidemic, collaborators will need to anticipate and address challenges spanning the complex vaccine development process, according to a New England Journal of Medicine perspective co-authored by researchers from the U.S. Army, industry and academia.

Col. Stephen Thomas, an Army infectious disease physician and vaccinologist specializing in flaviviruses such as Zika and dengue, is the lead author. He helped develop a promising Zika purified inactivated virus (ZPIV) vaccine at the Walter Reed Army Institute of Research (WRAIR). The other authors include Alan D.T. Barrett at the University of Texas Medical Branch and Maïna L’Azou and Nicholas A. C. Jackson with Sanofi Pasteur.

In this perspective piece, Thomas and his co-authors examine three successful flavivirus vaccines developed for yellow fever, tick-borne encephalitis and Japanese encephalitis, for lessons to guide Zika vaccine development. They identify a number of challenges, with various vaccine development activities, including:

• Defining a target product profile for the vaccine, which outlines dose level and schedule, delivery method, and the primary population to be vaccinated;

• Planning and executing clinical development processes which may prove to be difficult as the number of cases of Zika decline; and

• Scaling up vaccine production and manufacturing in order to produce the millions of vials needed to stem an outbreak in an endemic region.

Researchers from WRAIR created the Japanese encephalitis vaccine mentioned in the perspective piece, and they leveraged the Institute’s long history of flavivirus research to develop the ZPIV vaccine. “We’re building on technology WRAIR has already developed and successfully applied,” said Thomas. “We hope that by leveraging a proven technology we increase our chances of quickly developing a safe and effective Zika vaccine.”

Preclinical studies have found that WRAIR’s ZPIV vaccine candidate completely protected rhesus monkeys from experimental infection with two strains of the Zika virus. Phase 1 human trials are planned to begin in October at several sites in the US including WRAIR’s Clinical Trial Center in Silver Spring, Md.

“This type of rapid government, academic and industry collaboration we are seeing with Zika is truly unprecedented,” said Col. Nelson Michael, director of WRAIR’s Military HIV Research Program and Zika program lead. “While many challenges lie ahead of us, we are coordinating efforts with a broad array of public and private partners as never before to ensure the efficient development of a safe and effective Zika vaccine.

The authors conclude that maintaining momentum in Zika vaccine development activities will require seamless coordination between developers, regulatory agencies, WHO and the health authorities of affected nations, along with a robust monetary commitment from governments and funding agencies.