Under strict safety measures, no participants in staged concert got COVID-19
Under strict safety measures, no participants in a staged concert were infected with SARS-CoV-2, according to researchers, who said their experiment was the first randomized clinical trial to assess the risk of COVID-19 at mass gatherings.
Participants were tested before the 5-hour concert and made to wear N95 masks while inside, but there were no rules about distancing and researchers encouraged them to sing and dance during performances by two DJs and two live music acts.
Only people with a negative test were eligible to participate in the trial. Half of the around 1,000 people who participated attended the concert at the Sala Apolo venue in Barcelona, Spain, and the other half were sent home.
The results of the trial were published recently in The Lancet Infectious Diseases.
“We were contacted by professional promoters of cultural and musical activities in Barcelona and understood that if they wanted to safely reopen during the pandemic, under the existing strong recommendations of public health services across the world against those events, they would have to generate high-quality scientific data,” Josep M. Llibre, MD, PhD, a physician and researcher for the Fight AIDS Foundation, told Healio.
“Singing and mass-gathering events, particularly indoor events, had been considered high-risk activities for COVID-19 transmission. It had been estimated that every single person with COVID-19 could spread the infection to 10 to 15 contacts during those events. All huge events had been banned or the capacity reduced so much that the events were no longer profitable and the term ‘superspreader events’ was coined.”
For the study, Llibre and colleagues performed same-day screening of attendees with antigen-detecting rapid diagnostic tests (Ag-RDTs). The concert was held on Dec. 12, 2020. Adults with a negative result collected immediately before entering the event were randomly assigned in a 1:1 to either attend the indoor event for 5 hours or go home.
After 8 days, the researchers collected nasopharyngeal swabs and analyzed them by Ag-RDT, reverse transcriptase-PCR (RT-PCR) and a transcription-mediated amplification test (TMA). The primary outcome of the study was the difference in incidence of RT-PCR-confirmed SARS-CoV-2 infection at 8 days between the control and the intervention groups, assessed in all participants who were randomly assigned, attended the event and had a valid result for the SARS-CoV-2 test conducted at follow-up.
Overall, 1,140 attendees were eligible for the study, including 1,047 who were randomly assigned to attend the music event or leave. Of the 523 randomly assigned to the experimental group, 465 were included in the analysis of the primary outcome. Of the 524 randomly assigned to the control group, 495 were included in the final analysis.
According to the study, at baseline, 15 (3%) of 495 individuals in the control group and 13 (3%) of 465 in the experimental group tested positive on TMA despite a negative Ag-RDT result. Additionally, the RT-PCR test was positive in one case in each group and cell viral culture was negative in all cases. Eight days after the event, the researchers found that two (less than 1%) individuals in the control arm had a positive Ag-RDT and RT-PCR result, whereas no Ag-RDT or RT-PCR positive results occurred in the intervention arm.
“COVID-19 transmission in indoor mass-gathering events during the pandemic can be prevented with the implementation of preventive measures. These results have been key in the performance of concerts with a higher number of assistants and the approval of a program of events called ‘Events Research Programme’ by the public health department of the U.K,” Llibre said. “Similar programs are being implemented in Denmark, Norway and the Netherlands and, in addition, outdoor activities have a significantly lower risk and could probably reopen with all or even some of these three measures.”
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