An unauthorized person gained access to the immunization records of nearly 500 people, the Brant County Health Unit says.

According to the health unit, the recently discovered breach involves the records of 494 people who submitted information on their child’s immunization via the BCHU website between July 2015 and October 2015.

“The Brant County Health Unit has no evidence that the information has been used for dishonest purposes, but this incident is being taken very seriously,” the organization said in a press release.

The health unit says it is attempting to contact people affected by the security breach, and taking steps to ensure no similar incidents in the future.

Officials say a member of the public alerted them to the accessibility of the breached data.