A gel made by Endo Pharmaceuticals designed to prevent HIV has failed in a trial of more than 9,000 women, the UK’s Medical Research Council said.

A trial of vaginal microbicide Pro 2000 found no evidence that it reduced the risk of HIV when tested in women across four African countries.

The trial was the largest of its kind and is a blow to AIDS research.

A preliminary trial of Pro 2000 earlier this year indicated the gel may reduce the chances of contracting the virus by almost a third.