A smartphone app launched by the Canadian government to help slow the spread of COVID-19 could be less effective in the latest wave of the pandemic, says an expert.
The COVID Alert app, launched in July of 2020 by the federal government, works by using a cellphone's Bluetooth signal to detect other app users who come within two metres for at least 15 minutes.
If a user tests positive for COVID-19, they're supposed to receive a code from their local health authority, which they enter into the app.
Once that happens, any other app users who came within range of the infected person's phone will receive a notification warning them they've been exposed.
With PCR testing capacity limited in provinces across Canada, many users of the COVID Alert app likely aren't getting a one-time code needed to notify others of potential exposure, said Dr. Erica Moodie, a professor of biostatistics at McGill University.
Additionally, new evidence suggests the Omicron variant takes as little as three days to incubate, making the app even less effective in this latest wave, said Moodie, who took part in an independent study of the app earlier this year.
"If you had asked me pre-Omicron I would have said, 'Everyone needs this app actively all the time', and I certainly think there is no harm in having it. But I don't know if it's as effective now because of the apparent speed at which Omicron is being transmitted," she said.
Provinces across Canada have been reporting record-breaking daily case numbers in recent weeks, largely driven by the more transmissible Omicron variant.
Some provinces, including Quebec and Nova Scotia, announced that lab-based PCR testing will be reserved for select cases, while others who suspect they have COVID-19 are asked to use an at-home rapid test and isolate if it comes back positive.
"So a lot of people are not getting the PCR tests, they're doing rapid tests at home, which means you can't get... the activation key," Moodie said.
Even in provinces like New Brunswick, where everyone still has access to PCR testing, a backlog could mean that the wait for a positive result and one-time code for the app could come too late for it to effectively warn other app users of potential exposure.
"The PCR tests, where it used to take maybe 24 hours to get the results, it can take two or three days. And with Omicron being so transmissible and possibly incubating a little bit faster, a difference of a few days and a delay in getting that one-time key can make a big difference in terms of the transmission."
Health Canada did not respond to questions from CBC News about the effectiveness of the COVID Alert app at this stage of the pandemic.
CBC News also asked the Government of New Brunswick whether the rise in cases was affecting its ability to give app users the one-time code, but did not receive a response by deadline.
According to the Government of Canada, the app has been downloaded 6.7 million times and a total of 37,312 one-time codes have been given to users across nine provinces, but no provincial breakdown is provided.
As of April, the Canadian Digital Service, within the Treasury Board Secretariat, had spent $3.5 million to develop, maintain, test and secure the app.