Zika Vaccine Development Continues to Move Forward

Despite the ongoing funding stalemate in Congress, several research initiatives hoping to yield an effective vaccine against Zika virus are advancing through the development process.

Still, unless regulatory bodies such as the US Food and Drug Administration (FDA) and the World Health Organization (WHO) fast-track approval for these products, a viable vaccine is likely several years away.

After partnering with Walter Reed Army Institute of Research’s vaccine development project in July, drug manufacturer Sanofi Pasteur has won a $43 million grant from the US Biomedical Advanced Research and Development Authority (BARDA) to move the resulting product, called Zika purified inactivated virus, into Phase I/II trials, which are expected to begin in early 2018. If these trials are successful (ie, the vaccine is both safe and effective), BARDA has already committed another $130 million to fund follow-up trials.

Ultimately, the BARDA funds could also be used to finance production of the vaccine, BARDA acting director Richard Hatchett, MD, said in a statement. “Developing safe and effective vaccines is a priority in our strategy to protect the public health against the Zika virus,” he added. “This investment supports clinical trials and manufacturing of an additional Zika vaccine candidate that could help prevent Zika virus infection and the devastating birth defects that Zika virus can cause.”

BARDA and Walter Reed scientists began work on the Zika vaccine development program in March. In addition to its partnership with Sanofi, BARDA has also been collaborating with Takeda on another Zika vaccine initiative, providing $19.8 million in funding to the company to shepherd the product through preclinical work and Phase I trials. And, earlier in September, the agency announced a $125 million funding award to biotech firm Moderna, which is also working on a vaccine.

Meanwhile, the US National Institutes of Health (NIH) is working with GlaxoSmithKline on a Zika project that will use self-amplifying mRNA, or SAM to (hopefully) produce a vaccine. Human trials have not started as of yet, and no date has been announced.

Two virus DNA-based vaccines also in development at NIH have protected monkeys against Zika infection after two doses, according to a study published in Science. Based on these results, one of the vaccines has entered Phase I human trials, with at least 80 participants, in three US locations. If the trial results are favorable, NIH plans to initiate Phase II trials in Zika-endemic countries in early 2017. The second vaccine is awaiting a Phase I clinical trial start date.

Scientists from the Vaccine Research Center within NIH’s National Institute of Allergy and Infectious Diseases (NIAID) developed the experimental vaccines using circular DNA engineered to produce a particle mimicking the shape of the Zika virus. The experimental vaccines do not contain infectious material and thus cannot cause Zika infection. In their study, the researchers vaccinated groups of rhesus macaques using the two different experimental Zika DNA vaccines in different doses. They then exposed the monkeys to an infectious dose of Zika virus.

“NIAID worked expeditiously to ready a vaccine candidate, and results in animal testing have been very encouraging,” NIAID Director Anthony S. Fauci, MD, said in a statement. “Although it will take some time before a vaccine against Zika is commercially available, the launch of this study is an important step forward.”

Brian P. Dunleavy is a medical writer and editor based in New York. His work has appeared in numerous healthcare-related publications. He is the former editor of Infectious Disease Special Edition.