(PARIS) — The focus at a concert is usually on the band. But Saturday night, the focus at France’s Paris Accor Arena was on the crowd.

Some 5,000 volunteers got to go right up to the stage, sing along to their favorite songs and rub shoulders with other fans — all in the name of science.

Participants in the experiment were tested for COVID-19 in the three days before and on the day of the event, and they’ll be tested seven days later. That applies to the 5,000 attending Saturday’s concert and 2,500 from a control group that did not. A team of scientists then will compare the results.

During the show, led by the French rock band Indochine, artificial intelligence was used to monitor people’s behavior and respect of protocol, such as whether they kept their masks on, but no social distancing was in place. The band played for free, and no fee was asked of those attending.

After similar scenes in Barcelona and Liverpool, Paris authorities are spending over a million dollars in organizing one of the biggest experiment of its kind in Europe. If they can prove that there is no greater contamination at an indoors event of that size, it could lead to a return to concerts and live music as soon as this year. Concerts in France have been at a complete standstill since March 2020 because of pandemic lockdown measures.

The first results of the “AMBITION LIVE AGAIN” study are expected at the end of June and should help authorities optimize health protocols at future events. Professor Jean-Marc Treluyer, who’s in charge of the clinical trial, told ABC News that researchers are studying whether the number of cases seen in the concert-going crowd is equal to, or less than, that seen in the control group. They are using as reference a few smaller tests, including one in Barcelona in March, whose preliminary results showed no sign of contamination.

Almost 110,000 in France died from COVID-19, with the nation’s hospitals struggling to cope with the number of patients for several months, from March 2020 to May 2020, and then this year from February to April.

“We did not look at vaccination in this experiment because most young people are not vaccinated in France yet. In fact, we specifically selected participants between 18 and 45 years old who mostly aren’t vaccinated,” said Treluyer, who nevertheless agreed that an experiment on virus spread in vaccinated-only crowds would be interesting as well. According to France’s Health Ministry, 37.3% of the total population had received one dose of a COVID vaccine as of May 28.

Olivier Darbois, president of the concert venues and promoters union Prodiss, said the results of Saturday’s experiment coming back negative is “just not an option” and that France’s cultural sector can’t afford to wait much longer.

“The country lost $74 million of tourism revenue and shows like this bring tourists over,” Darbois told ABC News.

France lost $2.8 billion in live shows alone, according to Prodiss.

Entertainment professionals said they’re hoping the study’s results lead to rescheduling standing concerts, without physical distancing, as soon as the fall. So far, standing festivals are allowed this summer, but with a limit of one person every 4 square meters — and most festivals cannot be profitable with such restrictions.

“We might change the world together,” the rock singer Nicola Sirkis shouted at an ecstatic crowd.

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