Last week, the Centers for Disease Control & Prevention urged pregnant women and their partners to avoid a neighborhood north of Miami where Zika virus is known to be circulating. Zika has been linked to the neurological condition microcephaly in babies born to mothers infected with the virus. Now, scientists led by Dan H. Barouch of Beth Israel Deaconess Medical Center and Harvard Medical School report that vaccine candidates that previously provided protection against Zika virus in mice also work in rhesus monkeys—an animal model that’s a good predictor for humans (Science 2016, DOI: 10.1126/science.aah6157). The researchers studied three different types of vaccine candidates and found all to be effective against Zika strains. One vaccine candidate prepared from purified inactivated virus, which was developed by Barouch’s collaborators at Walter Reed Army Institute of Research, proved to be particularly potent. The researchers hope to begin Phase I clinical trials of the vaccine candidates in humans later this year, and the Army recently signed an agreement with Sanofi Pasteur to explore larger scale manufacture of the vaccine candidate made from purified inactive virus. In June, a different Zika vaccine candidate, from Inovio Pharmaceuticals and GeneOne Life Science, was the first to be approved by the U.S. FDA for Phase I clinical trials. The National Institute of Allergy and Infectious Diseases has another vaccine candidate in Phase I trials (see page 10).