More than 23 million people have been infected with the coronavirus globally, with over 806,000 deaths, according to Johns Hopkins University.

France reported the highest number of single-day new COVID-19 infections on Sunday since the country's lockdown measures were lifted. 

Italy also recorded the highest daily increase in COVID-19 cases since May 12. 

With infections surging in European countries in recent days, live concerts are still on hold. But researchers from the University of Halle in the German city of Leipzig came up with an experimental way to track the disease.

To understand how the coronavirus spreads at crowded events, researchers held a 1,500-person indoor concert on Saturday. 

Fans were given respiratory face masks, fluorescent hand gel and electronic "contact trackers" which help scientists determine the contact frequencies and distances between experiment participants.

Based on the residue left by fluorescent hand gel, researchers can determine which surfaces people touched frequently and required more safety measures to prevent the virus from spreading.

The experiment covers three scenarios including one that simulated a concert pre-coronavirus, a second simulating a concert during the pandemic, with improved hygiene measures in place, and a third, with reduced participants. 

Scientists will collect the data, build up a mathematical model, and evaluate the hygiene interventions, with conclusions ready by the end of the year.

"We cannot afford another lockdown," Professor Michael Gekle, the dean of the university's medical faculty and a professor of physiology said. "We have to gather the data now in order to be able to make valid predictions," he added.

The experiment is expected to help authorities draw up plans to reopen events in the upcoming autumn and winter seasons.

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