Same-Day SARS-CoV-2 Antigen Test Screening at Indoor Mass-Gathering

Quick Takes

  • The study was an open-label randomized trial comparing the incidence of SARS-CoV-2 infection between individuals with a negative SARS-CoV-2 rapid antigen test who participated in an indoor music event and individuals sent home.
  • The overall incidence of SARS-CoV-2 infection was low, with only two in the control arm testing positive at 8 days, and none in the intervention arm.
  • A screening strategy based on rapid antigen testing for SARS-CoV-2 may allow for safe mass-gathering events.

Study Questions:

Is same-day rapid antigen detection testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) effective at reducing the incidence of SARS-CoV-2 infection a week after social indoor gatherings?

Methods:

The study was an open-label clinical trial, which assessed the effectiveness of a rapid antigen testing-based strategy in preventing SARS-CoV-2 infections in adults ages 18-59 years invited to an indoor music event. Participants underwent same-day nasopharyngeal antigen testing for SARS-CoV-2, with those who tested negative randomized 1:1 to either attend the event for 5 hours or go home. All participants were then tested again 8 days after the event with both antigen and polymerase chain reaction (PCR) assays for the primary outcome of incident SARS-CoV-2 infection. All participants received an N95 mask, and mask wearing was mandatory during the entire event. Removing the mask was permitted only when drinking. No physical distancing was required. The total surface area of the venue was 1024 m2, and could accommodate over 2,000 people. The event was held in Barcelona, Spain on December 12, 2020.

Results:

A total of 465 took part in the event and 495 in the control arm were included in the analysis of the primary outcome. Participants included in the full analysis set had a mean age of 33.6 years (standard deviation, 8.6); 783 (82%) were men and 177 (18%) were women. Eight days after the event, two (<1%) individuals in the control arm had a positive antigen and PCR result, whereas no antigen nor PCR-positive results were found in the intervention arm.

Conclusions:

A mass-gathering indoor event of individuals who tested negative for SARS-CoV-2 using the rapid antigen test was not associated with a higher incidence of SARS-CoV-2 at 8 days.

Perspective:

Despite the significant advantages of rapid antigen testing for SARS-CoV-2 including low price, ease of implementation, and short turnaround time, the concern for relatively lower sensitivity compared to PCR has mitigated its use. This study provides reassuring data suggesting that individuals have a low risk of becoming infected with SARS-CoV-2 in a mass social gathering of people who had a negative rapid antigen test on the same day. It is important not to construe the findings as implying that mass gatherings during a pandemic are safe. Participants all tested negative on entry, selecting for a population at low risk of transmission. The study was also conducted at a time when the number of COVID-19 cases had hit its trough in Barcelona, Spain, implying that the overall risk of SARS-CoV-2 transmission at the time was low. Deployment of mass-screening strategies timed to events is also challenging with regard to organization, costs, training, and staffing. Nevertheless, the study provides valuable data to help guide the design of strategies related to screening and policies for mass gatherings, which have varied dramatically across the world and have mostly relied on anecdotal evidence and expert opinion.

Clinical Topics: Prevention

Keywords: ACC COVID-19 Podcast, Coronavirus, COVID-19, Immunologic Tests, Masks, Mass Screening, Music, Polymerase Chain Reaction, Primary Prevention, SARS-CoV-2


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