Scientists found all three offered protection in tests on rhesus monkeys.

Zika has been deemed a public health emergency, because it can cause serious birth defects.

Teams around the world are working to design a vaccine that can be given to people, but it is likely to be years before any is ready for widespread use.

More than 60 countries and territories now have continuing transmission of Zika, which is carried by mosquitoes.

(BBC News)