Sanofi Pasteur has announced that it is developing a vaccine for the Zika virus, which is spreading rapidly across the Americas.

This makes Sanofi the first major pharmaceutical company to launch a project for a Zika vaccine, although some smaller firms and academic institutions have already begun the search. A consortium including US Biotech Inovio Pharmaceuticals has said it could have a vaccine ready for limited emergency use by the end of the year, while GSK has said it is investigating whether its vaccine technology is suitable before announcing firm plans.

"Sanofi Pasteur is responding to the global call to action to develop a Zika vaccine given the disease's rapid spread and possible medical complications," said Nicholas Jackson, research head of Sanofi Pasteur. The company believes its existing expertise in vaccines for dengue – which is closely related to Zika – could help it identify a candidate more quickly.

Earlier this week the World Health Organisation declared the spread of Zika to be an international public emergency. Although the disease typically causes mild fevers and rashes, it is also linked to underdeveloped brains, or microcephaly, in newborn children.