COVID-19 risk mitigation in reopening mass cultural events: population-based observational study for the UK Events Research Programme in Liverpool City Region

Objectives: To understand SARS-CoV-2 transmission risks, perceived risks, and the feasibility of risk-mitigations from experimental mass cultural events before COVID-19 restrictions were lifted.

Design: Prospective, population-wide observational study.

Setting: Four events (two nightclubs; outdoor music festival; business conference) open to Liverpool City Region UK residents, requiring a negative lateral flow test (LFT) within the 36 hours before the event, but not requiring social distancing or face-coverings.

Participants: 12,256 individuals attending one or more event between 28th April and 2nd May 2021.

Main outcome measures: SARS-CoV-2 infections detected using audience self-swabbed (5-7 days post-event) PCR tests, with viral genomic analysis of cases, plus linked NHS COVID-19 testing data. Audience experiences were gathered via questionnaires, focus groups and social media. Indoor CO₂ concentrations were monitored.

Results: 12 PCR-positive cases (likely 4 index; 8 primary or secondary), 10 from the nightclubs. Two further cases had positive LFTs but no PCR. 11,896 (97.1%) participants with scanned tickets were matched to a negative pre-event LFT: 4972 (40.6%) returned a PCR within a week. CO₂ concentrations showed areas for improving ventilation at the nightclubs. Population infection rates were low, yet with a concurrent outbreak of >50 linked cases around a local swimming pool without equivalent risk-mitigations. Audience anxiety was low and enjoyment high.

Conclusions: We observed minor SARS-CoV-2 transmission and low perceived risks around events when prevalence was low and risk-mitigations prominent. Partnership between audiences, event organisers and public health services, supported by information systems with real-time linked data can improve health security for mass cultural events.