Pfizer Inc. has stopped a mid-stage clinical trial for a staph infection vaccine after an external group of experts determined that the trial would likely not meet its main goal.

The company said it is evaluating next steps for the development of the vaccine, meant to prevent Staphylococcus aureus infections in patients who are undergoing spinal fusion surgery.

The vaccine, called PF-06290510, was found to be safe in the planned interim analysis, and patients will complete the study's follow-up evaluations, the New York-based company said.