In a largely unvaccinated population, a Covid-19 infection control strategy involving point-of-contact screening, mask wearing, and enhanced ventilation was associated with low SARS-CoV-2 transmission at an indoor concert with 5,000 attendees held in Barcelona, Spain in March 2021.
At the time of the concert only around 6% of Barcelona residents were vaccinated against Covid-19, with most vaccines being given to nursing home residents, elderly people and health care workers. The age standardized 14-day cumulative incidence rate of Covid-19 in the city was roughly 259 per 100,000 people at the time.
Six unvaccinated concert goers were diagnosed with Covid-19 in the 2 weeks after the event, confirmed by polymerase chain reaction testing. But 3 of the 6 were found to be exposed to someone with Covid-19 outside the concert setting.
Careful follow-up of the concert goers in the 2 weeks after the event revealed that Covid-19 incidence among the cohort was roughly half that of the general population (130.9 cases per 100, 000 persons).
Writing in Annals of Internal Medicine, published online July 19, researchers Josep Llibre, MD, PhD, and Sebastia Videla, MD, PhD, of Barcelona’s University Hospital Germans Trias i Pujol, wrote that the findings suggest the combination of same-day antigen-detecting rapid diagnostic testing (Ag-RDTs), masking and enhanced ventilation “can prevent high rates of SARS-CoV-2 transmission in indoor mass-gathering live concerts without physical distancing.”
“These findings must be read in the context of a case study conducted in a community with low vaccination rates and a moderate infection rate. Nevertheless, they are a key step for creating safe environments in not only live music events but also other mass-gathering events,” they wrote.
Llibre and Videla’s research report follows their previously published randomized controlled study where they found preliminary evidence that such mitigation strategies work.
In commentary published with the observational study, Carolee Estelle, MD, and Trish Peri, MD, both of UT Southwestern Medical Center, Dallas, characterized the low rate of SARS-CoV-2 transmission following the mass gathering event as “promising” evidence that mitigation strategies other than social distancing may be effective in populations with low rates of vaccination against the virus.
“Although such findings are encouraging and provide a potential safe path for large indoor events, some important considerations remain,” they wrote, adding “How does one choose the ideal test and evaluate test characteristics to effectively implement a safety protocol for large events?”
The editorial writers noted that the sensitivity of the available SARS-CoV-2 protocols varies widely from test to test—from around 40% to over 90%—and this variation is especially pronounced among people with asymptomatic disease.
They further noted that employing the testing strategy for mass gathering events remains “logistically challenging and costly.”
In an interview with BreakingMED, Estelle emphasized the importance of the combination of infection mitigation efforts for preventing SARS-CoV-2 transmission at large, mass gathering events.
She said due to the logistical and financial challenges of implementing point-of-care screening at large indoor gatherings like sporting and music events, such screening is not likely to occur routinely in areas where vaccination rates are relatively high, such as the United States.
Because of this, other infection control measures such as masking and enhanced ventilation will remain important as these large indoor events ramp up, she said.
“People really want to get back to doing these things, but they also want measures in place to make them feel safe,” she said. “This is especially true in places like Texas, where I live, where vaccination rates are not as high as we would like and cases are increasing, partly due to the emergence of the Delta variant.”
The Barcelona observational study included participants who attended an indoor live music concert held at an indoor stadium on the afternoon of March 27, 2021.
Between 8 a.m. and 3 p.m. on the day of the event, a team of 74 nurses performed AG-RDTs (Panbio Covid-19 AG Rapid Test) on all 5,000 attendees at 3 screening sites.
Filtering facepiece 2 masking was mandatory for all attendees during the event, but singing and dancing was allowed, and no physical distancing was required.
All attendees were located on the central floor of the stadium, which was at full capacity. No one was allowed in the stadium stands, which had a capacity of 13,000.
Ventilation was maximized to provide 6 complete air changes every hour.
Six of the 5,000 screened people tested positive and were not allowed to attend the concert. Six concert attendees— one of whom were vaccinated— were diagnosed with Covid-19 in the weeks after the event (median age 36 years, range 27-46 years). Three of the 6 were identified during contact tracing studies of known index cases who had not attended the concert.
The researchers wrote that despite the limitation that “the pragmatic approach of the study precludes direct comparisons between the incidence rate observed among attendees and that of the background population,”….”our data indicate that no remarkable transmission events occurred during the concert and support that Ag-RDT may be suitable for ruling out individuals with transmission risk at the time of testing rather than identifying infected individuals.”
In a largely unvaccinated population, a Covid-19 infection control strategy involving point-of-contact screening, mask wearing and enhanced ventilation was associated with low SARS-CoV-2 transmission at an indoor concert with 5,000 attendees.
Six unvaccinated concert goers were diagnosed with Covid-19 in the 2 weeks after the event, confirmed by polymerase chain reaction testing, but 3 of the 6 were found to be exposed to someone with Covid-19 outside the concert setting.
Salynn Boyles, Contributing Writer, BreakingMED™
This research was funded by the Festivals for Safe Culture, Barcelona, Spain.
Cat ID: 190
Topic ID: 79,190,730,933,190,926,192,927,925,934
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