The United States, Japan and others tightened travel curbs to virus-hit China while businesses struggled with supply problems from the epidemic that has infected nearly 10,000 and been declared a global emergency.

Christophe D'Enfert, a scientific director with the Pasteur Institute, told reporters in Paris the vaccine could be made available in 20 months if "all goes well."

"At the end of August, we could enter clinical trials and, provided all goes well, obtain a vaccine candidate within 20 months."

There is currently no vaccine available against the coronavirus but several organisations including the Coalition for Epidemic Preparedness Innovations (CEPI), a public-private body based in Norway, are working at developing one.