For a project called “RESTART-19,” scientists with the University Medical Center Halle (Saale) plan on throwing a concert with 4,000 fans and a German music artist in an indoor arena to simulate how people move, gather and spread potentially coronavirus-infected germs.

But there’s a catch: participants must test negative for SARS-CoV-2, the virus driving the pandemic, and wear a mask at all times aside from snack and outdoor breaks, according to their website.

The team says data on how respiratory diseases spread in large events is “sparse overall and practically nonexistent for COVID-19,” so they want to fill in the gaps.