Canada’s COVID Alert app prevented up to 7,900-plus infections and 74 coronavirus deaths in Ontario from March to July last year, according to a new study.
The Canadian Journal of Public Health recently published a study which analyzed the effectiveness of the app on reducing cases and deaths due to the COVID-19 virus.
The app was launched in the summer of 2020 as a way to alert people if they’ve been in close contact with someone who was infected with the virus.
The study found that the app averted between 6284 and 10,894 infections across six provinces (Manitoba, Newfoundland and Labrador, Nova Scotia, Ontario, Quebec, and Saskatchewan) where app usage was highest between March and July 2021.
This range is equivalent to 1.6 to 2.9 per cent of the total recorded infections across Canada in that time period.
In addition, 57 to 101 deaths were averted during the same time period.
“While the nationwide rates are low, provinces with widespread adoption of the app showed high ratios of averted cases and deaths (upper bound was greater than 60 per cent of averted cases). This finding suggests that the COVID Alert app, when adopted at sufficient levels, can be an effective public health tool for combatting a pandemic such as COVID-19,” the authors wrote.
Ontario had the largest proportion of those estimates with 4,567 to 7,917 cases and 42 to 74 deaths averted due to app usage. Manitoba had the second largest proportion with up to 1,148 infections and 12 deaths prevented.
The researchers said they used two approaches to find their results, including a comparative study to assess the adoption and usage of the app compared to similar ones deployed in other countries, such as the USA, France, Germany, Italy and Netherlands.
The second approach involved collecting data from the COVID Alert server and estimating the number of cases averted in each province based on the authors’ chosen modeling approach.
“…(The model) combines information on number of notifications, secondary attack rate, expected fraction of transmissions that could be prevented, quarantine effectiveness, and expected size of the full transmission chain in the absence of exposure notification,” the authors wrote.
The researchers noted that they limited the assessment to the aforementioned six provinces as more than 200 notifications were sent on the app in each of those regions between March and July 2021.
Unsurprisingly, the results show that the ratio of cases averted to confirmed cases were overall higher in areas where a larger proportion of the population adopted the app.
“Most notably, the results indicate that the proportion of app users is positively associated with the ratio of cases averted to cases, which supports the positive intervention effects of COVID Alert on reducing the burden of the disease,” the authors wrote.
Although Ontario had the largest number of cases and deaths averted, the impact in terms of the proportion of cases and deaths averted was greatest in Newfoundland and Labrador.
“Overall, our findings give support to the use of exposure notification apps as tools in the mitigation and management of epidemic events. For such apps to be useful, however, they must be sufficiently adopted and protocols around their usage implemented,” the authors wrote.
The researchers noted some limitations in the study, including insufficient data available to provide reliable comparisons of notification apps across different countries.
In addition, the modeling analysis was unable to estimate key parameters “due to the high level of data aggregation employed to preserve privacy.”
Last month, Health Canada shut down the app due to low usage, declining case counts and hospitalizations, and the lack of polymerase chain reaction testing across Canada.