Scientists with the Walter Reed Army Institute have just started the first of five early stage clinical trials for a Zika virus vaccine. Early preclinical trials in July showed that two doses of the vaccine administered four weeks apart induced an immune response to Zika in rhesus monkeys. It is the only inactivated vaccine for Zika virus that is undergoing clinical trials.
The scientists are recruiting 75 health adults who have never been infected with any flaviviruses and will also test the vaccine in people who have been vaccinated against Japanese encephalitis and yellow fever. The studies will evaluate the safety and effectiveness of the vaccines over a shortened time period and its ability to prevent Zika in people who have been infected with dengue.
If this phase of the clinical trial suggests that the vaccine is safe and effective, the vaccine will advance to another series of clinical trials run by Sanofi Pasteur.
One of the researchers, Kayvon Modjarrad, says that a vaccine will not be available for another two to three years. However, he also says that this is an improvement over the usual decade-long timeline for vaccine development. He attributes this to increased investment in laboratories and streamlined regulations since the 2014 Ebola outbreak, as well as to lessons learned from previous studies on dengue, yellow fever, and Japanese encephalitis.