Contact tracing apps may reduce Covid outbreak: Study

A model of Covid-19 spread within a simulated population found that if about 20 per cent of the population adopted a contact tracing app on their smartphones, an outbreak could be reduced by about 35 per cent.

If more than 30 per cent of the population adopted the app, the epidemic could be suppressed to manageable levels, said researchers, including Livio Bioglio from the University of Turin.

The team noted that the effectiveness of digital contact tracing would depend on a given population's level of immunity to the virus; the intervention alone would be unable to suppress a Covid-19 epidemic where transmission -- and especially asymptomatic transmission -- remains high.

For the study, published in the journal Science Advances, the team developed a model that simulates a synthetic French population based on census data from the National Institute of Statistics and Economic Studies (INSEE).

The researchers used this synthetic population to explore the impact of digital contact tracing -- as well as detection of Covid-19 cases, quarantines, and isolation of household contacts -- under scenarios in which the virus was more or less transmissible based on the prevalence of face mask use and hand washing.

They found that when the virus was highly transmissible, household isolation alone reduced Covid-19 cases by 27 per cent, while pairing this strategy with digital contact tracing reduced Covid-19 cases by 35 per cent when only 20 per cent of the population adopted the app.

Simulating increased rates of app adoption also led to further reductions in cases, the team said.