Contact tracing apps may stem Covid-19 spread even when only a few use them: Study

Contact tracing apps can sharply reduce the spread of the novel coronavirus even when only a few people use them, a study published on Thursday by researchers at Google and Oxford University showed.

An app used by 15% of the population together with a well-staffed contact-tracing workforce can lead to a 15% drop in infection rates and an 11% drop in Covid-19 deaths, according to statistical modeling by the Alphabet Inc unit and Oxford's Nuffield Department of Medicine.

With a 15% uptake of contact tracing apps alone, the researchers calculated an 8% reduction in infections and 6% reduction in deaths.

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The findings were based on data from a digital tracing system similar to one jointly developed by Google and Apple Inc.

The app made by the two tech giants tracks interactions through Bluetooth signals and anonymously notifies a person if someone they met contracts Covid-19.

Six US states and about two dozen countries have launched exposure notification apps based on the Apple-Google technology in recent weeks without major hitches.

The researchers simulated the spread of Covid-19 based on interactions at homes, offices, schools and social gatherings in Washington State's King, Pierce and Snohomish counties.

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"We see that all levels of exposure notification uptake levels in the UK and the US have the potential to meaningfully reduce the number of coronavirus cases, hospitalizations and deaths across the population," Christophe Fraser, the study's co-lead author and group leader in Pathogen Dynamics at Oxford University's Nuffield Department of Medicine, said in a statement.

The researchers noted that a contact tracing app is not a stand-alone intervention. They also said their model still represents a "dramatic simplification of the real world", and does not take into account cross-county movement of people contributing to disease spread.

The research, however, has not been peer-reviewed.