Analysis of three types of Zika vaccines reveal that they are effective at protecting rhesus monkeys from the virus, a new study reports. Whereas some similar techniques and vaccines have been tested in mice, monkeys are a much better model to determine how vaccines will work in humans. Zika has been causally associated with fetal microcephaly, intrauterine growth retardation, and other birth malformations in humans. A preventative vaccine is poised as one of the best ways to minimize the spread of the virus and its detrimental effects. Previously, researchers including Peter Abbink and Dan Barouch had reported that both a DNA vaccine and a purified inactivated virus (PIV) vaccine were effective at protecting mice from the virus. Now, Abbink et al. report the efficacy of the PIV virus in 16 rhesus monkeys, eight of which were given sham vaccines as controls. All PIV vaccinated animals developed Zika-specific binding and neutralizing antibodies two weeks following immunization, and were completely protected from Zika when exposed to the virus. When the researchers harvested antibodies from Zika-PIV vaccinated monkeys and transferred them to mice and monkeys, a technique called adoptive transfer, these animals also were protected against Zika virus, as long as therapeutically sufficient antibody titers were transferred. The researchers also tested a DNA vaccine and a recombinant adenovirus (Ad) vector expressing the Zika pre-membrane and envelope protein. These two vaccines also raised antibody responses and provided full protection to monkeys, and the Ad vector even protected after a single immunization. Across all three platforms, no adverse effects were reported.