HALIFAX -- New Brunswick has joined three other provinces in getting their health authorities to offer "one-time keys" to users of the COVID Alert app.

The app notifies users if they may have been exposed to someone who has tested positive for COVID-19.

"Users who test positive for COVID-19 will receive a one-time key from their health authority that they can enter into the app," Health Canada said in a news release. "When the key is entered, COVID Alert will notify other users who may have come in close contact with that person for at least 15 minutes, and direct them on next steps based on their provincial public health advice."

The app was launched in July and the technology has been vetted and approved by Canada's privacy commissioner.

COVID Alert is available for download across Canada, but one-time keys are only available in New Brunswick, Ontario, Newfoundland and Labrador, and Saskatchewan.

"The Government of Canada continues to work with the other provinces and territories to bring their health authorities on board in the coming weeks and months," the release said.