Canada's COVID-19 Alert app updated to include more precise exposure information

Prime Minister Justin Trudeau says the COVID Alert app can now provide more precise information to people who are exposed to the virus.

There have been approximately 4.9 million downloads of the federal COVID-19 exposure notification app so far, with 2,939 Canadians using it to report a positive coronavirus test. Alberta and B.C. are the final two provinces that have yet to activate the app. 

Trudeau says users who test positive for COVID-19 can enter the time their symptoms started, or the date they were tested. This information is important to figure out when they were most infectious to others, and those who are exposed can better estimate the time period they were at risk.

Health Canada said in a statement Friday the tweak aligns more closely with public health guidance, as symptomatic individuals are most infectious from two days before their symptoms began. 

The new features are optional and the additional data will not be shared with the government or anyone else, according to Health Canada.

Until now, COVID Alert was designed to deliver exposure notifications to all users who were in extended close contact with an infected person over the past 14 days.

B.C.'s provincial health officer, Dr. Bonnie Henry said earlier in the week the province remained reluctant to use the app while its exposure notifications were "very non-specific."

"What we really would like to see is an app that we could download when we're at a celebration or a party or a church service, so that we can identify those specific times when there may have been somebody with COVID who was in that vicinity," Henry said on Monday.

Lucie Vignola, a director of Health Canada's COVID-19 task force told CBC News this week the federal agency is also considering adding compatibility with wearable devices. The move could make the tool available to Canadians who don't own a smartphone.

"We're always looking to see how we can further improve the app ... while maintaining that main aspect of privacy," Vignola said.