Guidance

Descriptive and feasibility study of risk-mitigation with SARS-CoV-2 antigen rapid lateral flow testing to reopen live events 

Updated 8 September 2021

Project Summary

This study aims to compare SARS-CoV-2 PCR test positivity pre- and post-attendance at an Events Research Programme (ERP) event.

Event organisers will invite applicants to attend events. Those registering interest will be asked to consent to participation in the research. They will be informed that whilst risk mitigation measures will be in place, there remains a residual and unquantifiable risk of contracting COVID-19. 

Those consenting to participate will be directed to book a supervised SARS-CoV-2 antigen rapid lateral flow device (LFD) test at an Asymptomatic Testing Site (ATS). Entry to the event will be conditional on demonstrating a negative LFD test taken in the 36 hours prior to the event. If the LFD test is positive, participants will be asked to self-isolate and take a confirmatory PCR test, in accordance with national guidance. For events in Liverpool, their LFD result will be linked to the event ticketing through their health record system CIPHA. Elsewhere, if event organisers are unable to link to CIPHA a variety of methods will be used to verify the test result, including manual checking of the confirmatory email or SMS message at entry.

There are challenges to reliance on ATS testing which may introduce bias to attendance and make some events unviable. Therefore, self-administered LFD testing at home will be used for the final two events of the ERP. 

At the time of booking an LFD test, all event goers will also be asked to order a PCR test 3 days in advance of the event to be taken on the day of the event, and a postal PCR test on Day 5. There is variation in how home PCR tests will be arranged depending on event timing: 

• Those attending events pre-dating 30 April will be asked to order a home PCR test 3 days in advance of the event to be taken on the day, and a home PCR test to be performed on day 5;

• For events occurring on or after 30 April, PCR tests will be routinely posted to event goers using ticketing data.

Any positive tests will be reported through Test and Trace and contact tracing undertaken to ascertain detail of activity during the day of the event including travel, seating and activity at the venue. Local contact tracing hubs may pick up some of this work, including the Cheshire and Merseyside hub for Liverpool events.

All positive PCR tests with a Ct value of less than 30 will be genome sequenced to identify clusters of SARS-CoV-2 infections, indicating potential transmission at the event. Note that due to lab process issues, a maximum of 89% of cases detected from the events that pre-date 30 April will undergo genomic sequencing; this will be closer to 100% for events occurring on or after 30 April (individual test Ct values permitting).

Details of the test results associated with the ERP will be extracted from the results databases held within Test and Trace either by NHS number or by matching against name and postcode. 

Data will be obtained, processed, stored and analysed in accordance with information governance protocols. Personal identifiers will not be stored and data will be analysed using unique identifiers attached to record level data. Statistical analysis will be done using SPSS.

Results will be published in anonymised format.

Background and rationale

The ERP is exploring the use of COVID-19 risk-mitigation strategies to support reopening a variety of events and venues, as part of the government’s Roadmap for COVID-19 recovery. The Roadmap describes plans to explore when and how events with large crowd sizes, less social distancing, or in settings where transmission risk is high without mitigation, may be able to return safely.

Sports, entertainment, social and business functions that are currently restricted carry unknown risks of SARS-CoV-2 transmission, particularly regarding the latest variants. So, there is a need to mitigate the likely increases in transmission due to social mixing at such events/venues. Currently a range of non-pharmaceutical interventions (NPIs) are used to mitigate risk, but these impact on the participant experience and satisfaction as well as the commercial viability of events whilst the relative contribution of such interventions to controlling the transmission of COVID-19 is not known.

The ERP will use events incorporating research studies in April and May 2021 to build evidence of the risks associated with coronavirus transmission, the characteristics of events and surrounding activities, and the most effective steps for reducing these risks. The evidence from these studies will be used to inform the government’s decisions around Step 4 of the Roadmap—removal of all legal limits on social contact, reopening of any remaining premises, including nightclubs, and easing of restrictions on large events, performances, weddings, and other life events—and will help shape government policy to bring about the phased return of fuller audiences to venues and events. Step 4 of the Roadmap will take place no earlier than 21 June.

The ERP will draw findings from the evaluation of a series of scientifically instrumented events run by stakeholders across a range of venue types (including indoor and outdoor) and sectors (arts, creative industries, business, and sport events). Building the evidence base across a range of settings will enable more tailored mitigation measures to be considered rather than one-size fits all approaches (such as current capacity caps). The results of the testing evaluation will be aligned with the outputs from the concurrent research studies on ventilation, crowd behaviour and social distancing to inform risk mitigation measures for Stage 4 of the Roadmap.

Aims and objectives

The aim of this study is to provide evidence on the feasibility of pre-event rapid antigen testing with LFDs for SARS-CoV-2 in mitigating the risk of COVID-19 transmission amongst spectators, participants or audiences at cultural and sporting events, instrumented with and pre- and post-event PCR testing.

The objectives of this study are to:

1. Estimate the PCR test uptake rate per event and pooled across all events, and identify individual- and event-level factors that are associated with PCR test uptake rate.

2. Estimate the rate of index cases and potential secondary cases in event goers per event and pooled across all events, and describe the variation by individual- and event-level factors.

3. Identify event-related clusters using genomic sequencing data.

4. Understand the data flows required to enable future research on the transmission of SARS-CoV-2 at events.

5. Undertake a gap analysis of events-related contact tracing, to identify what level of detail is currently collected by the national Contact Tracing and Advisory Service (CTAS) and the opportunities for collecting specific events-related information from cases.

The study research questions are:

1. What proportion of those who attend the events:

• complete their LFD test at an asymptomatic test site (ATS) as per protocol (for events dated 17 April-11 May),

• return a completed pre-event home test PCR kit, 

• return a completed post-event home test PCR kit, and

• return both completed pre-event and post-event home test PCR kits?

2. What proportion of those who attend the events:

• receive a PCR positive test result indicative of them attending the event already infected (i.e. index cases), and 

• receive a post-event PCR positive test result and is suspected to be a secondary case (e.g. pre-event PCR negative test result)?

3. Using whole genome sequencing of positive home test PCR kits:

• how many likely secondary (event-transmitted) cases were detected with post-event PCR tests and are linked by their genomic sequencing results, and 

• can genomic sequencing of pre-event PCR positive tests identify a linked index case?

If enough high-quality data is available (i.e. assuming sufficient matching between ticketing and testing data, as well as an adequate PCR return rate), the following research questions will also be explored: 

• the difference in post-event incidence rate of SARS-CoV-2 infection between events with no index cases identified and events where index cases were identified, 

• associations between post-event PCR positivity, and individual- and event-level characteristics, in those who had a negative pre-event PCR test result, and

• associations between genomically-confirmed cluster size and event-level characteristics.

Methods

There are 4 indoor events at small to medium sized venues and 6 outdoor events, as detailed in the table that follows. The venues will host a range of sporting and cultural events with audiences of varying size and capacity for the venues. There are 3 multi-day events.

Date	Event	Location	Attendees	Event type
18-Apr	FA Cup Semi-final	Wembley, London	4,000	Outdoor seated
17 April-3 May	Snooker World Championships	Crucible Theatre, Sheffield	<1,000/day	Indoor seated
25-Apr	Carabao Cup	Wembley, London	8,000	Outdoor seated
28-Apr	Good Business Event	Arena, Liverpool	300	Indoor mixed – open/seated
30-Apr-1 May	Circus Nightclub	Bramley Moore Dock, Liverpool	3,000 and 4,000	Indoor open
02-May	Live National Outdoor Music Event	Sefton Park, Liverpool	6,000	Outdoor unstructured
11-May	Brit Awards	O2, London	5,000	Indoor seated (mixed styles)
15-May	FA Cup Final	Wembley, London	21,000	Outdoor seated
15-May	Mass Participation Run	Kempton Park, Surrey	18,000	Outdoor unstructured
Maximum sample size:			c. 86,300

This study aims to compare SARS-CoV-2 PCR test positivity pre- and post-attendance at an ERP event.

Every event goer will undertake an LFD test in the 36 hours prior to the event. Only those able to demonstrate a negative test result, and declaring no symptoms, will be permitted entry to the event. For all events, other than the FA Cup Final and the Mass Participation Run, event goers will be required to undertake their pre-event LFD test at an ATS. For the FA Cup Final, 9,000 Club Wembley event goers attending the FA Cup Final will be randomised to either home LFD test or ATS LFD test, with the remaining 12,000 spectators (travelling fans) required to undertake their pre-event LFD test at an ATS. For the Mass Participation Run, event goers will be given the choice of whether to undertake their pre-event LFD test at an ATS or at home.

Event goers at the Snooker World Championships attending multi-day events on successive days, will be asked to take an LFD test at an ATS every 3 days, and can only participate in the study if all tests are negative. If an LFD test is positive, the event goer must not attend the event and, in accordance with national guidance, they must self-isolate and take a confirmatory PCR test. To assess the transmission of COVID-19 at the event itself and the effectiveness of pre-event LFD testing in identifying those infected with SARS-CoV-2, event goers will also be asked to provide a home PCR test on the day of the event and a home PCR test five days after the event.

All positive PCR tests with a Ct value of less than 30 will be genome sequenced to identify clusters of SARS-CoV-2 infections, indicating potential transmission at the event. Note that due to lab process issues, a maximum of 89% of cases detected from the events that pre-date 30 April will undergo genomic sequencing; this will be closer to 100% for events occurring on or after 30 April (individual test Ct values permitting).

Any positive tests will be reported through Test and Trace and contact tracing undertaken to ascertain detail of activity during the day of the event including travel, seating and activity at the venue. Local contact tracing hubs may pick up some of this work, including the Cheshire and Merseyside hub for Liverpool events.

Data will be obtained, processed, stored and analysed in accordance with information governance protocols. Personal identifiers will not be stored, and data will be analysed using unique identifiers attached to record level data. Results will be published in anonymised format.

Sample size

The study population is around 86,300 people attending one or more of the events comprising the ERP phase 1. The analyses are mainly descriptive in nature, and no formal power size calculation is presented. The main focus is on the feasibility of testing (matching between ticketing and testing data and PCR return rate) and its utility for outbreak management and forward events planning under different epidemic state scenarios.

Data collection

The event organisers will send a list of all event goers who attended the event to PHE, using secure transfer methods. Event goer information (self-reported name, date of birth, sex and full address) will be linked to NHS number using the Demographic Batch Service. NHS number will be used to link to the Pillar 2 testing dataset, for the time-period from 36 hours prior to 7 days following the event. A 7-day post-event cut-off will be used to capture those who might receive a positive result earlier (e.g. if they become symptomatic) and those who might return their sample late. Genomic sequencing data from the final events will take longer to come through due to lab processing times – expected processing time upper limit of 9 days – therefore, a further data look-up of PCR-confirmed cases in event goers against sequencing data will be necessary at a later timepoint.

If an NHS number cannot be matched via the Demographic Batch Service, probabilistic data matching techniques will be used to attempt to link event goer information to the Pillar 2 testing dataset. Event goer data linkage will be performed with other datasets to allow the use of socio-demographic and other data (such as ethnicity, vaccination and deprivation data). 

Data analysis and reporting

Test results will be obtained from the databases held within Test and Trace, and linked using personal identifiers. Records will then be allocated a unique identifier, personal identifiers removed, and all analysis undertaken on the anonymised records in a secure analytical environment.

The full statistical analysis plan (v2.4) is reported separately.

Results will be aligned with those from other nested studies to form a report on the role of LFD testing in mitigating the risk of COVID-19 transmission at mass events. This will be presented to government ministers to inform the government roadmap on COVID recovery.

Results will submitted to peer review and published on Open Research.