Saturday’s statement from AstraZeneca said the independent U.K. investigation into the event has concluded and it advised the Medicines Health Regulatory Authority, Britain’s equivalent of the Food and Drug Administration, that it was safe to resume the trial. The MHRA concurred and gave the green light for the trial to restart.

The illness that triggered the international pause, which occurred in a woman who was in the vaccine arm of the U.K. trial, has not been officially disclosed, though AstraZeneca CEO Pascal Soriot told a group of investors on Wednesday that her symptoms were consistent with transverse myelitis, a serious condition involving inflammation of the spinal cord that can cause muscle weakness, paralysis, pain and bladder problems.

The AstraZeneca statement said information about the illness the woman suffered cannot be disclosed. Oxford University, where the vaccine was developed, said in a separate statement that the nature of the illness cannot be revealed “for reasons of participant confidentiality.”