Rapid screening, face masks may prevent SARS-CoV-2 transmission at indoor mass-gathering events

An observational study in Barcelona, Spain found that implementation of same-day rapid screening, use of face masks, and improved ventilation was associated with very low rates of SARS-CoV-2 transmission at an indoor mass-gathering live concert without physical distancing. The brief research report is published in Annals of Internal Medicine.

Indoor mass-gathering events have been banned since the beginning of the COVID-19 pandemic because of the high risk for the spread of SARS-CoV-2. Protocols are needed to prevent virus transmission during such events.

Researchers from Germans Trias i Pujol Hospital, Barcelona, Spain studied electronic health records to determine if previously tested containment measures could prevent high rates of transmission during an indoor live music concert with 5,000 attendees. On-site nurses screened all attendees with an antigen-detecting rapid diagnostic test (Ag-RDT) and filtering facepiece 2 masks were required to be worn during the entire event. Singing and dancing were allowed, and no physical distancing was required. An analysis of 4,584 attendees found 6 cases of COVID-19 within the 2 weeks after the concert. Of those 6 persons, 3 were identified in contact-tracing studies of known index cases who had not attended the concert; therefore, their contagion was unlikely to occur during the event. One woman may have had COVID-19 and attended the event during the incubation period. The transmission source of the 2 remaining cases could not be identified.

The authors note that the study was conducted in a community with low vaccination rates and a moderate infection rate. Nonetheless, they conclude that their findings have implications for informing safety measures at similar mass-gathering indoor events.