Nearly 450 patients treated at Salem Hospital in Massachusetts could have been exposed to hepatitis and HIV due to improperly administered IV drugs.

“Earlier this year, Salem Hospital was made aware of an isolated practice involving a small portion of endoscopy patients who were potentially exposed to infection due to the administration of their intravenous medication in a manner not consistent with our best practice,” according to a statement from Mass General Brigham (MGB), the health care system Salem Hospital belongs to. (Endoscopies involve a doctor inserting a tubelike instrument into a patient’s body to capture images of specific tissues.)

“Once identified, the practice was immediately corrected, and the hospital’s quality and infection control teams were notified,” according to the statement, which was shared with Live Science via email. The practice involved a single contracted individual who no longer works at Salem Hospital, MGB spokesperson Adam Bagni added in an email.