Federal COVID Alert app wasn't working for some users for much of November

The developers of Canada's COVID Alert appfixed a glitchlast week that left some users without exposure notificationsfor much of November.

An update to the app released on Nov. 23 said it would fix a "bug causing gaps in exposure checks for some users." Without the patch, some Canadians running the app would not have been notified if they came in close contact with someone diagnosed with COVID-19.

It's unclear how many people missed exposure notifications due to the glitch. But it does raisethe prospect that certain users weren't advised to self-isolate or seek a COVID-19 test in a timely manner, potentially delaying diagnosis.

"For two weeks, the app basically didn't work" for those users, said Urs Hengartner, an associate professor of computer science at the University of Waterloo.

He and otherson social media said their devices had not performed any exposurechecks from Nov. 9 to 23. The process when a smartphone receives codes from a central server and verifies whether the user was potentially exposed to someone with COVID-19 is supposed to take place several times a day.

WATCH|How the COVID Alert app works

The problem appears to have first been reported by commenters in the Google Play Store as early as Nov. 12. That's 11 days before it was fixed.

"I noticed today that COVID Alert has done no exposure checks for the last two weeks," a user wrote in Apple's App Store on Nov. 20. "What good is this?"

Users are urged to check their app store (the Google Play Store for people with Android devices and Apple's App Store for those with iPhones) to ensure their app is now up to date. Users who haven't installed the latest update version 1.1.2 could still be missing exposure checks.

COVID Alert is designed to take note when two users spend at least 15 minutes less than twometres apart. If a user later tests positive for COVID-19, they can use the app to anonymously notify contacts of potential exposure.

COVID Alert has been downloaded more than 5.5 million times and is touted by federal officials as a tool to help slow the spread of the virus. The app is active in the Northwest Territories and all provinces except Alberta and B.C.

During the two-week period in November when some users reported the malfunction, 1,182 people used the app to report a positive test in Ontario alone, according to provincial data.

COVID-19 infection ratescontinued to rise across much of the country during that time. Ontario, for example, announced lockdown measuresin its two most populous regions, andP.E.I. and Newfoundland and Labrador both announced on Nov. 23 they would withdraw from the Atlantic bubble due to increasing case counts elsewhere in the region.

Bianca Healy, a spokesperson for the Treasury Board of Canada Secretariat, which houses the app's development team,confirmed in an email Thursday evening that"on some devices, if the app was not opened by the user for an extended period of time, COVID Alert would stop checking in the background for the random codes that would trigger a notification that a user may have been exposed to COVID-19. This bug has now been fixed."

Healy said the app's built-in privacy features prevent federal officials from knowing how many users may have been affected.

"We encourage Canadians to update COVID Alert as soon as possible," she wrote. "They can also open the app to ensure that COVID Alert is checking for potential exposures."

Hengartner, the computer science professor, said it is"a little concerning that it took two weeks to fix this bug." He saidboth he and his wife experienced the same issue.

He called it "a fatal bug for this kind of system," as it defeatsthe purpose of the app entirely.

It's unknown what caused the glitch, but Hengartner said he suspects it was an error in a previous COVID Alert update.

Users weren't immediately warned

Smartphone users can choose to automatically receive app updates or download them manually. Apple's App Store lists 14 updates for COVID Alert since its initial release in July.

The Canadian Digital Service, the federal agency responsible for developing the app,tweeted a message on Nov. 26 asking users to make sure they have the latest COVID Alert update. "This will ensure your app is doing what it's supposed to do, and you're not missing any checks or notifications," the message read.

The tweet did not mention that the scenario it described was real and posed a potential risk to some users. It's unclear what other steps the federal agency took to alert users of the importance of the latest update.

Hengartnerstressed the problemshould not discourage Canadians from installing COVID Alert.

However, Kelly Bronson, a Canada Research Chair in science and society,saidthe episode does highlighthow the app could provide users with a "false sense of security." She pointed to "automation bias," a human tendency to rely on automateddecision-making, which can reduce personal vigilance.

Bronson, who serves on the Global Pandemic App Watch program at the University of Ottawa, which tracks the uptake of similar tools around the world, warned the apps "are not a panacea."

"I think it's really important that people know the limitations of these technologies," she said.