A new and improved vaccine for the Zika virus has been developed after an epidemic swept across the Americas in 2015.

Zika triggered travel warnings, with pregnant women being urged to postpone non-essential trips to affected countries during a surge in cases which revealed the mosquito-borne virus could cause birth defects.

Governments, academic laboratories, and pharmaceutical companies invested heavily in stopping the virus.

The committed public health efforts paid off, with Brazil declaring an end to its Zika emergency in May after a drop in cases.

However the World Health Organisation has warned that tens of millions of people could still be infected in the Americas in the coming years.


There are currently no licensed vaccines or therapeutics available to combat Zika, although a $100m US government-led clinical trial is underway.

Image: Twins born with microcephaly in Areia, Brazil

Now, researchers from Arizona State University (ASU) in the US have developed the world's first plant-based Zika vaccine.

They believe this vaccine could be "more potent, safer, and cheaper to produce" than the other medicines being developed.

"Our vaccine offers improved safety and potentially lowers the production costs more than any other current alternative, and with equivalent effectiveness," said ASU scientist Dr Qiang Chen.

Dr Chen is a specialist in developing plant-based vaccines and has previously worked to develop therapeutics and vaccines for West Nile virus and Dengue fever, which belong to the same family of viruses as Zika.

His Zika vaccine targets a key protein which envelopes the outside of the virus.

By developing this protein by itself, without the dangerous virus within it, it could be used to immunise people to the real strain of Zika.

Dr Chen's team performed immunisation experiments on mice and found a 100% success rate in inducing antibody and cellular immune response to protect against multiple Zika virus strains.

But while the virus is effective, it is not foolproof, and can cause serious side effects.

"Above all, we have to ensure the utmost safety with any Zika vaccine, especially because the people who will need it most, pregnant women, have the most worries about their own health, and the health of the fetus," said Dr Chen.

"This has to be 100% safe and effective."

Zika is associated with a birth defect called microcephaly when contracted by pregnant women. It can result in children being born with abnormally small heads and brain damage.

The virus, first discovered in Uganda in 1947, leaves those infected with mild flu-like symptoms and can also be sexually transmitted.