Vaccine giant Sanofi Pasteur has quietly pulled the plug on its Zika vaccine project, a move that underscores how difficult it may be at this stage to develop a vaccine against the virus.

The company announced the move in a statement posted on its website at 3 p.m. Friday, pointing to a decision by a federal funding body to scale back spending on Zika-related research. Sanofi said BARDA — the Biomedical Advanced Research and Development Authority, an arm of the Department of Health and Human Services — informed the company in mid-August that it was reducing its financial assistance for Sanofi’s Zika vaccine project.