Answering criticism that the federal "COVID Alert" app only works on newer smartphones, Dr. Theresa Tam says it's one of many tools in fighting the novel coronavirus.
The app released last week is meant to tell users if their phones have recently been close to a phone registered to someone who volunteers that they've tested positive for COVID-19.
But it works only on phones released in the last five years or so because it needs a relatively recent operating system.
Critics say that will leave out poorer and older Canadians, who are more likely to use older devices and suffer worse effects from the virus.
The government said Monday that 1.1 million people had downloaded the app.
Tam says we need to use every tool we have to fight the pandemic, even if they aren't perfect.