Covid-19 contact-tracing apps need high adoption to be successful
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Researchers have looked into the effectiveness of contact-tracing apps, such as those introduced in many countries since the start of the pandemic.
The team from Queen Mary University studied the effectiveness of Spanish app, Radar Covid, following a four-week experiment conducted in the Canary Islands, Spain, between June and July 2020.
They simulated a series of Covid infections in the capital of La Gomera, San Sebastián de la Gomera, to understand whether the app’s technology could work in a real-world environment to contain a Covid-19 outbreak.
They found that over 30 per cent of the population adopted the technology and it was able to detect around 6.3 close-contacts per infected individual, which was over two times higher than the national average detected using manual contact tracing alone.
However, they said the app’s success is dependent on effective national and local communications campaigns to encourage people to download and use the app in the first place.
Dr Lucas Lacasa, author of the study, said: “Whilst digital contact tracing has been suggested as a valuable complement to manual tracing programmes, and even already been adopted in several countries, until now we haven’t had any real experimental evidence to prove the effectiveness of this technology.”
“Overall, our results were positive and show that the technology works and, if accompanied by appropriate communications campaigns, it should reach the levels of adoption and compliance needed to support other non-pharmaceutical interventions to contain outbreaks.”
Contact-tracing apps rely on the use of mobile phone apps to trace contacts and notify individuals of recent contact with others who have recently tested positive for Covid-19.
Concerns have been raised regarding their use, such as the potential detection of a high number of false close-contacts, low adoption and adherence and privacy issues.
“Some of the concerns from the healthcare sector around digital contact tracing relate to whether these apps could trigger avalanches of false close-contacts and, as a result, false positives that could overwhelm primary healthcare resources,” said professor Alex Arenas, one of the study’s authors.
“However, we didn’t see this in our experiment and the number of close-contacts detected was about the same amount we’d expect from existing data. We also saw that the adoption was above the threshold needed for the app to be efficient.”
Radar Covid is based on the Apple/Google protocol and adopts a privacy-by-design approach, aiming to maintain user anonymity with features such as a lack of login or identification requirements and the user’s ability to remove or deactivate the app at any time.
The UK’s Covid-19 tracing app finally launched in September 2020, after the initial version of the app was scrapped after functioning poorly on iPhones.
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