By Douglas Busvine

BERLIN (Reuters) – A fitness tracker app launched this spring in Germany to monitor the spread of COVID-19 indicates that recently imposed social-distancing measures have yet to slow a second wave of infection, the scientist leading the project told Reuters.

Over half a million people have connected their smartwatches and fitness trackers to the Corona-Datenspende (Corona Data Donation) app, making it possible to construct a ‘fever curve’ based on readings such as pulse or steps taken.

An elevated pulse can reveal that a person is running a high temperature, while they would take fewer steps if they feel unwell. Taking the readings together can serve as a basis for estimating COVID-19 infection trends.

Crunching that raw data requires adjustments and, after tweaks to the app’s algorithm to take into account that people tend to exercise more in good weather, that fever curve now serves as a reliable leading indicator of COVID-19 trends.

“At the moment we can see that the fever curve seems to precede the case count by between three days and a week,” said Dirk Brockmann, of the Institute for Theoretical Biology at the Humboldt University in Berlin.

That’s the good news. The bad news is that extensive social restrictions announced last week and imposed across Germany from Monday – including shutting restaurants, gyms and theatres – have yet to have a decisive impact.

“The curve is still heading upwards – it looks more linear but we don’t see a bending of the fever curve,” added Brockmann, who also leads a project group at the Robert Koch Institute that models how infectious diseases spread.

Brockmann emphasized that the fever curve does not provide an accurate forecast of infections – but it can flag important shifts in trend or turning points.

The Robert Koch Institute, Germany’s center for disease control, reported a record daily COVID-19 caseload on Friday of 21,506, bringing the total since the outbreak of the pandemic to 619,089. The death toll rose by 166 to 11,096.

The Corona Data Donation app, developed with healthtech startup Thryve, works on wearable devices such as Apple Watches or Fitbit fitness trackers.

(Reporting by Douglas Busvine; Editing by Keith Weir)