The latest European concert experiment saw a crowd of 5,000 attendees pack into the Palau Sant Jordi arena in Barcelona, Spain for the country’s largest concert in nearly a year. The concertgoers were part of an experiment that saw all of them receive rapid testing before the concert. Though masks were required at all times at the event, ticket-holders were not forced to socially distance from one another.

This comes as the latest concert experiment across Europe, including a trial in the Netherlands last week which saw 1,500 fans attend a two-day music festival near Amsterdam. Ahead of the concert on Saturday in Barcelona, which featured Spanish rock band Love of Lesbian, all attendees received a rapid COVID-19 antigen test on their way inside the arena. Of the first 2,400 people tested, only three returned positive results and were sent home.

“This is for one night only, so enjoy it,” one of the hosts said before the concert started at Saint Jordi.

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This event followed a successful trial run of 500 attendees for a show back in December, so doctors and promoters alike decided to push the capacity variable up to 5,000 people. This latest experiment differed from the one with 500 people as there was no control group outside of the arena.

While the show appears to have been a success, the true results will be seen in the next 14 days as attendees monitor their health. Back in December, a concert at Sala Apolo in Barcelona resulted in zero infections after 463 attended the indoor event.

“We expect it to be completely safe. Over the next 14 days we will look at how many of the audience test positive for Covid and will report back,” doctor Josep Maria Llibre told the AFP news agency.

The concert took place with the full permission of local health authorities and the cooperation of medical researchers. Attendants were able to choose between three venues at which to receive a rapid COVID-19 test on Saturday morning. The show sold out within hours, with the roughly $20 ticket covering the cost of admission, the rapid test, and a face mask.

“This is another small step toward being able to hold concerts and cultural events” during the pandemic, said Dr. Boris Revollo, the virologist who helped design the health protocols.

Watch a full report on the latest concert experiment in Barcelona via Bloomberg.

Barcelona’s Covid Concert Experiment