Researchers in Spain have shared heartening results from the first randomized controlled trial to assess risk for COVID-19 transmission at an indoor live music concert.
The study, published May 27 in The Lancet Infectious Diseases, led by virologist Boris Revollo, MD, from the Germans Trias i Pujol University Hospital in Barcelona, included comprehensive safety measures.
It was conducted on Dec. 12, 2020, at a time when local travel restrictions were in place, indoor meetings were limited to six people, and vaccines were not yet available.
All 465 event attendees got same-day SARS-CoV-2 screening with antigen-detecting rapid diagnostic tests before they entered, wore masks throughout, and followed crowd-control measures in the well-ventilated venue, which can hold up to 900 people.
The control group consisted of 495 participants randomly assigned to go home instead of attending the concert after the screening.
None of the attendees tested positive for SARS-CoV-2 infection by polymerase chain reaction (PCR) test 8 days after the 5-hour event, but two in the control group did.
In fact, the study showed that the risk for infection was no higher among those at the concert than it was for those who lived in the same community and did not attend.
The Bayesian estimate for the incidence between the test and control groups was –0.15% (95% confidence Interval, –0.72 to 0.44).
“Our findings pave the way to reactivate cultural activities halted during COVID-19, which could have important sociocultural and economic implications,” the authors wrote.
All wore masks throughout
Among the comprehensive safety measures were that, in addition to testing, all attendees had their temperature checked before gaining access and were given an N95 face mask, which had to be worn at all times inside.
Hand sanitizer was provided in multiple locations, access doors remained open to allow fresh air to circulate, and the coat room was closed to prevent clustering.
There was no mandated distancing, people could sing and dance, and alcohol was available in a bar located in a separate room – and drinks were allowed only in that space.
Rosanna W Peeling, PhD, professor and chair of diagnostic research at the London School of Hygiene and Tropical Medicine in the United Kingdom, and David L. Heymann, MD, of the department of infectious disease epidemiology there, said in an accompanying commentary that there is a great need for studies like this one to help build evidence for a return to normal gatherings.
“So many countries don’t have any policy or any way of doing this because they don’t have the evidence,” Dr. Peeling said in an interview.
The study was well done and a strength was the testing 8 days later, which can be hard to do for similar events when people disperse to locations outside the community where the event or gathering was held, she said.
Study prompts additional questions
Dr. Peeling and Dr. Heymann wrote that the work raises questions such as whether triple-layered masks would have been sufficient. Or how does rapid antigen testing at the entrance compare with molecular screening within 72 hours of entering?
They noted that there are questions around whether existing rapid diagnostic tests are able to detect COVID-19 variants.
Dr. Peeling said that these kinds of results need to be shared and shared more quickly, “if we’re ever going to get out of this pandemic.”
Studies like this are also difficult, she noted, because they may involve non–health sector entities such as city governments and concert organizers working together with researchers.
In addition, the safety measures come at considerable expense and it’s unclear whether those could be employed routinely at such events.
“It’s not really sustainable at sports events with 20,000 people,” Dr. Peeling said.
Infectious disease expert William Schaffner, MD, of Vanderbilt University, Nashville, Tenn., told this news organization that the study results “come a little late to the party.”
If this study had been done in today’s era with authorized vaccines, “it would have been a moot issue,” he said. “The mask is a barrier to transmission, but we now have a much more solid barrier we could put in place, which is vaccination.
“That said, it does reinforce the fact that classical mask wearing does really offer protection even in a crowded venue,” Dr. Schaffner said.
He added that the study was relatively small and he’d like to see it replicated in larger concerts or group gatherings.
Dr. Peeling and Dr. Heymann report no relevant financial relationships. A coauthor is an employee and stockholder of Primavera Sound, sponsor of the study. All other authors declare no relevant financial relationships.
A version of this article first appeared on Medscape.com.