Single shots of either one of two types of vaccine can protect susceptible mice against the Brazilian Zika virus, reports a paper published online in Nature this week. The findings bring the prospect of a human Zika vaccine one step closer.

It is widely accepted that Zika virus infection can cause neurological problems, including microcephaly and Guillain-Barre syndrome. This led the World Health Organization to declare Zika virus infection a global public health emergency. The development of a safe and effective Zika virus vaccine is thus a priority, but little is known about the immunology of the virus and mechanisms of immune protection.

Dan Barouch and colleagues tested candidate vaccines in mouse models of Zika virus infection. They show that single immunizations with one of two types of vaccine - one made from DNA, the other a purified inactivated form of the virus - gave the mice complete protection against an isolate of the Zika virus from northeast Brazil. Inoculated animals produced antibodies that recognized specific viral proteins, and the extent of protection correlated with the level of these antibodies. Although care should be taken extrapolating from this mouse study to potential human efficacy, the research raises hopes that a safe, effective human vaccine will become feasible.