Doctors are one step closer to creating a Zika vaccine, after testing on mice successfully protected them against the virus.
The mosquito-borne virus has been declared as a global public health emergency by the World Health Organisation. The virus is spreading rapidly and has strong links to a serious birth defect, microcephaly, which causes babies to be born with abnormally small heads and brain damage.
A report published online in scientific journal Nature says single shots of two types of vaccines can protect susceptible mice.
Little is known about the immunology of the virus and mechanisms of immune protection, the report says, making the development of a safe and effective Zika virus vaccine a priority.
Two vaccines were tested on mice which had been infected with the Zika virus, by Dr Dan Barouch and his colleagues in the US.
The results show "single immunisations 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".
Antibodies found in the immunised mice were able to recognise proteins specific to the Zika virus, the report says, and a link was found between the level of protection the animals had and the level of the antibodies.
While the study was done on mice, it raises hope an effective vaccine is achievable.
The risk is to people travelling to the Americas and the Pacific Islands, particularly pregnant women. Athletes have been considering the risk of Zika ahead of the Olympics in Rio, with golfer Rory McIlroy being the latest to pull out.