Germany has allowed three music events to be held on the same day to study the transmission risks posed by mass inside events during the pandemic.
Scientists from Halle University carried out the experiment, named Restart-19, with 1500 healthy volunteers aged between 18 and 50.
Each of Saturday's gigs, all performed by German singer-songwriter Tim Bendzko, was set up slightly differently. The first had no safety measures in place. The second involved greater hygiene and some social distancing, while the third involved half the number of participants and each person stood 1.5 metres apart.
All audience members were tested for COVID-19 before taking part, and were provided with face masks and tracking devices to measure their distancing. Fluorescent disinfectants were also used to monitor the most common touch points.
The study came after Germany recently recorded its highest number of new coronavirus cases since the end of April. According to reports, more than 2000 cases were recorded in 24 hours, bringing the total number of cases to more than 232,000. The country's death toll remains below 10,000.
The findings from the study are due to be published in the autumn.