Screening before music concerts and mass sport events

Screening for SARS-CoV-2 Antigen Before a Live Indoor Music Concert: An Observational Study
On the day of the event, a team of 74 nurses performed Ag-RDTs for all attendees. The use of filtering facepiece 2 masks was mandatory. Singing and dancing were allowed, and no physical distancing was required. All attendees were located on the central floor of the stadium, which was at full capacity. Of the 5000 Ag-RDT–screened individuals, 6 (prevalence, 120 cases per 100 000 persons) tested positive and were not allowed to enter the concert, as well as 2 of their close contacts despite testing negative. The final analysis included 4584 attendees. Six attendees (1 man and 5 woman; median age, 36 years [range, 27 to 46 years]), none of whom were vaccinated, were diagnosed with COVID-19 within the 2 weeks after the concert (median, 8.5 days [range, 4 to 12 days]). Three of them had been located in the front-right area of the stadium and 3 in the front left. Of these 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 who participated in the event was oligosymptomatic, though she tested negative in the pre-event Ag-RDT screening and again 48 hours after the event; 4 days after the concert, COVID-19 diagnosis was confirmed by PCR testing. Therefore, she presumably attended the event during the incubation period. The transmission source of the 2 remaining cases could not be identified. Our results build on our previously reported clinical trial data (2) and suggest that the implementation of same-day Ag-RDT screening, use of face masks, and improved 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.

COVID and mass sport events: early studies yield limited insights
[Nature news report.] Just 28 of the more than 55,000 people who took part as spectators at events — including the World Snooker Championship at a Sheffield theatre, the Football Association cup final at Wembley Stadium and the BRIT Awards at the O2 Arena in London — tested positive for SARS-CoV-2. Of these, researchers identified 11 who might have been infectious at an event and a further 17 as potentially infected at or around the time of an event, according to the findings, published on 1 July. The report’s authors urge these figures to be interpreted with “extreme caution” because the virus was not circulating widely in the community at the time and only 15% of those required to return pre- and post-event PCR tests did so.

Events Research Programme: Phase I findings
[UK policy paper.] The variation of transmission risk factors within a venue matters as well as the differences in risk between types of venue. Outdoor spaces are generally lower risk than indoor spaces. However, all venues are different and may have indoor spaces such as toilets, food/drink concessions and corridors which can pose higher risks. Large unstructured gatherings indoors where there is significant mixing of people in close proximity typically pose a higher risk. Mitigation options include: communications, crowd and audience management strategies, face coverings, ventilation, testing, restrictions on food and drink, and social distancing/capacity caps. It is challenging to generate robust, generalisable evidence of the transmission risk associated with particular events.

Mitigating COVID-19 infection disease transmission in indoor environment using physical barriers
In this study, the impact of barrier heights on the spread of aerosol particles is investigated in an open office environment with the well-designed ventilation mode and supply air rate. The risk of infection disease transmission is evaluated using simulation of particle concentration in different locations and subject to a number of source scenarios. It was found that a barrier height of at least 60 cm above the desk surface is needed to effectively prevent the transmission of viruses. For workstations within 4 m from the outlet, a 70 cm height is considered, and with a proper ventilation mode, it is shown that the barriers can reduce the risk of infection by 72%. However, for the workstations further away from the outlet (beyond 4 m), the effect of physical barrier cannot be that significant.

A cluster randomised trial of the impact of a policy of daily testing for contacts of COVID-19 cases on attendance and COVID-19 transmission in English secondary schools and colleges
[Preprint.] Of 99 control and 102 intervention schools, 76 and 86 actively participated. There were 657 symptomatic PCR-confirmed infections during 7,782,537 days-at-risk (59.1/100k/week) and 740 during 8,379,749 days-at-risk (61.8/100k/week) in the control and intervention arms respectively (ITT adjusted incidence rate ratio, aIRR=0.96 [95%CI 0.75-1.22;p=0.72]) (CACE-aIRR=0.86 [0.55-1.34]). Rates of symptomatic infection in contacts were 44/4665(0.9%) and 79/5955(1.3%), respectively (aOR=1.21 [0.82-1.79;p=0.34]). Daily contact testing of school-based contacts was non-inferior to self-isolation for control of COVID-19 transmission. COVID-19 rates in school-based contacts in both intervention and control groups were <2%. Daily contact testing is a safe alternative to home isolation following school-based exposures.